What about the specifications of expansion screws?
Expansion screws are widely used in China, that is, casing type.
The formal specification of casing type is M 1XM2XL, where M 1 stands for tooth diameter, M2 stands for casing outer diameter and l stands for length. For example, M6X8X40. However, the expression of l is somewhat different. Take the hexagonal nut of gecko with flange sleeve as an example, clamp the nut to the place parallel to the tooth profile, and then measure the total length from the flange surface to the cone head screw with caliper. The length l of the hexagonal shell gecko represents the total length of the thread, but does not include the thickness of the hexagonal head.
What do you think of the size of the expansion screw?
1. Usually, the characteristic code of thread is the letter "m": bolt specification M 14, which means metric bolt with thread diameter of14 mm. .m stands for "metric, metric" thread. Generally speaking, a complete thread mark consists of: thread feature code+size code+tolerance zone code+other information+standard code;
2. Size code: Generally speaking, the size code of a single thread is also "nominal diameter × screw torque". For thick threads, the item of marking the spiral torque can also be omitted. The size code of multi-thread is "nominal diameter ×Ph lead P screw torque".
3. The code of the tolerance zone is represented by data words, followed by letters (capital letters for internal threads and lowercase letters for external threads), such as 7H and 6g. At this time, it should be pointed out that 7H and 6g represent thread tolerances, while H7 and g6 represent cylindrical tolerance codes.
4. Generally speaking, the thread length is short (represented by S), medium (represented by N) and long (represented by L). Generally, the thread engagement length is not marked, and the thread tolerance zone is determined according to the medium engagement length (n).
5. Left-handed threads should also be marked with "LH" after tightening the length. You can use "-"to separate the screw-in length code from the screw-in direction code, and omit the right-hand thread.
Conclusion: That's all about how to look at the specifications of expansion screws. We know that there are many norms, so we must know how to treat them. If you want to know more about it, you can pay attention to our Qijia. Com for consultation.