The manufacturer of sleeper screws tells you that the thread is a shape with uniform spiral protrusions on the cross-section of the solid outer or inner surface. According to its structural characteristics and uses, it can be divided into three categories:
(1) Ordinary thread: the tooth shape is triangular, which is used to connect or fasten parts. The manufacturer of sleeper screws tells you that ordinary threads are divided into coarse thread and fine thread according to the pitch, and the connection strength of fine thread is higher.
(2) Transmission thread: the tooth shape is trapezoidal, rectangular, saw-shaped and triangular.
(3) Sealing thread: The sleeper screws manufacturer tells you that it is used for sealing connection, mainly pipe thread, taper thread and taper pipe thread
Thread fit level:
The manufacturer of sleeper screws tells you that the thread fit is the size of the loose or tight between the screw threads, and the level of fit is the specified combination of deviations and tolerances acting on the internal and external threads.
(1) The sleeper screws manufacturer tells you that for unified inch threads, there are three thread grades for external threads: 1A, 2A and 3A, and there are three grades for internal threads:
Class 1B, 2B and 3B are all clearance fits. The sleeper screws manufacturer tells you that the higher the level number, the tighter the fit. In the inch thread, the deviation is only specified for 1A and 2A grades, the deviation of 3A grade is zero, and the grade deviations of 1A and 2A are equal. The larger the number of grades, the smaller the tolerance,
1. Class 1A and 1B, very loose tolerance class, which is suitable for the tolerance fit of internal and external threads.
2, 2A and 2B grades are the most common thread tolerance grades specified for inch series mechanical fasteners.
3. For 3A and 3B grades, the screwing forms the tightest fit. The sleeper screws manufacturer tells you that it is suitable for fasteners with tight tolerances and is used for the key design of safety.
4. The sleeper screws manufacturer tells you that for external threads, 1A and 2A have a matching tolerance, and 3A does not. The 1A tolerance is 50% larger than the 2A tolerance and 75% larger than the 3A tolerance. For internal threads, the 2B tolerance is 30% larger than the 2A tolerance. Class 1B is 50% larger than Class 2B and 75% larger than Class 3B.
(2) Metric thread, external thread has three thread grades: 4h, 6h and 6g, internal thread has three thread grades: 5H, 6H, 7H. (Japanese standard thread accuracy grades are divided into three grades: I, II, and III. Normally, it is grade II.) In metric threads, the basic deviation of H and h is zero. The basic deviation of G is positive, and the basic deviation of e, f, and g is negative.
1. The sleeper screws manufacturer tells you that H is a commonly used tolerance zone position for internal threads, and is generally not used as a surface coating, or a very thin phosphate layer. The basic deviation of G position is used in special occasions, such as thicker plating, which is generally rarely used.
2. The sleeper screws manufacturer tells you that g is commonly used to plate a thin coating of 6-9um. For example, the product drawing requires a 6h bolt, and the thread before plating uses a tolerance zone of 6g.
3. The sleeper screws manufacturer tells you that the thread fit is best combined into H/g, H/h or G/h. For the thread of refined fasteners such as bolts and nuts, the standard recommends the use of 6H/6g.