1, external shape: ACME is a common trapezoidal thread; STUBACME is also a trapezoidal thread, which belongs to short tooth Akram rib.

2. Application: ACME is the most common, and universal female thread should be adopted; STUBACME is used in special occasions where space is limited.

According to the user's arbitrary design outer diameter and number of teeth per inch, we can provide relevant thread plug gauges and ring gauges for ACME and STUB-ACME threads. They are all American trapezoidal ribs (ACME).

The English word for short tooth is stubbacme, with a tooth angle of 29, which consists of outer diameter size, number of teeth per foot and tolerance code. The expression method is as follows:1/2-16 stubbacme-2G, 2g accuracy grade. The thread precision grade may not be marked in the design drawing, and the working tooth profile of this thread is short and there are more teeth per inch, so users can use it.

Extended data:

The marking of trapezoidal thread consists of thread code, tolerance code and thread length code, separated by "—". According to national standards, trapezoidal thread code is expressed by type code Tr and thread "nominal diameter × lead". Because the standard only specifies a tolerance zone (4H, 4h) for the minor diameter D 1 of internal thread and the major diameter of external thread, the basic deviation of specifying the tolerance position of minor diameter d3 of external thread as h is always zero.

The tolerance level is the same as the tolerance level of the middle diameter, but for the large diameter D4 of the internal thread, the standard only stipulates that the lower deviation (that is, the basic deviation) is zero, and there is no upper deviation. Therefore, trapezoidal thread is only marked with the tolerance zone of middle diameter, which represents the tolerance of trapezoidal thread (composed of numbers representing the tolerance zone grade and letters representing the tolerance zone state). Threads are divided into three groups, and the resolution is called short thread length (S) and medium thread length (N).

In general, the middle screw length (n) is often used and can be omitted. The tolerance codes of trapezoidal thread pairs are respectively marked with the tolerance zone codes of internal and external threads, with the tolerance zone codes of internal threads at the front and external threads at the back, separated by diagonal lines.

Baidu Encyclopedia-English Thread

Baidu encyclopedia-trapezoidal thread