The difference between ACME and STUBACME threads:
1. External shape: ACME is an ordinary trapezoidal thread; STUBACME is also a trapezoidal thread, which is a short-tooth Acram thread.
2. Application occasions: ACME is the most common, and general-purpose AC female threads should usually be used; STUBACME is used in special occasions with limited space.
Both ACME and STUB-ACME threads can provide relevant thread plug gauges and ring gauges according to the user's arbitrarily designed outer diameter and number of threads per inch. They are all American-made trapezoidal ribs (ACME).
The English expression of ACME is STUB ACME, 29° tooth form angle, which consists of outer diameter size, number of teeth per foot, and tolerance code. The expression method is such as: 1/2-16STUB ACME-2G , 2G accuracy level. The design drawings do not need to indicate the thread accuracy level. This thread has a short working tooth profile and a large number of teeth per inch. The user can design the relevant number of teeth per inch. We can provide thread plug gauges as required. , ring regulations.
Extended information:
The marking of trapezoidal thread consists of thread code, tolerance code and screwing length code, separated by "—". According to the national standard, the trapezoidal thread code is represented by the type code Tr and the thread "nominal diameter × lead". Since the standard only stipulates one tolerance zone (4H, 4h) for the small diameter D1 of the internal thread and the large diameter of the external thread, it stipulates that the external thread The tolerance position of small diameter d3 is always zero and the basic deviation of h is zero.
The tolerance grade is the same as the pitch diameter tolerance grade. For the internal thread large diameter D4, the standard only stipulates that the lower deviation (i.e. the basic deviation) is zero, but does not specify the upper deviation, so the trapezoidal thread is only marked Pitch diameter tolerance zone, and represents the tolerance of trapezoidal threads (consisting of a number indicating the level of the tolerance zone and a letter indicating the location of the tolerance zone). The screwing length of the thread is divided into three groups, namely short screwing length (S), medium screwing length length (N) and long length (L).
Under normal circumstances, the medium screw length (N) is commonly used and does not need to be marked. The tolerance code of the trapezoidal thread pair indicates the tolerance zone code of the internal and external threads respectively. The front is the tolerance zone code of the internal thread, and the back is the tolerance zone code of the external thread, separated by a slash in the middle.
Baidu Encyclopedia--Imperial thread
Baidu Encyclopedia--Trapezoidal thread