Threaded fasteners are commonly used for classification and matching level inventory
1. Ordinary thread: The tooth shape is triangular and used to connect or fasten parts. Ordinary threads are divided into coarse teeth and fine thread according to the pitch, and the connection strength of the fine thread is high.
2. Transmission thread: The tooth shape has trapezoid, rectangle, saw shape and triangle.
3, sealing thread: for sealing connection, mainly for pipe thread, taper thread and taper pipe thread.
Thread fit level
The thread fit is the loose or tight size between the threaded threads, and the level of fit is the specified combination of deviations and tolerances on the inner and outer threads. For uniform inch threads, the external threads are available in three thread grades: 1A, 2A and 3A, and internal threads are available in three grades:
Levels 1B, 2B and 3B are all clearance fits. The higher the level number, the tighter the fit. In the inch thread, the deviation only specifies the 1A and 2A levels, the 3A level deviation is zero, and the 1A and 2A level deviations are equal.
The larger the number of grades, the smaller the tolerance
1, 1A and 1B grade, very loose tolerance class, which is suitable for tolerance fit of internal and external threads.
2, 2A and 2B, is the most common thread tolerance class specified by the British series of mechanical fasteners.
3, 3A and 3B, screwing to form the tightest fit, suitable for tight tolerance fasteners, for critical design of safety.
4. For external threads, 1A and 2A have a tolerance, and 3A does not. The 1A tolerance is 50% larger than the 2A tolerance and 75% larger than the 3A. For the internal thread, the 2B tolerance is 30% greater than the 2A tolerance. Level 1B is 50% larger than 2B and 75% larger than 3B.
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 grade is divided into I, II, IIIXX, under normal conditions is grade II) In the metric thread, the basic deviation of H and h is zero. The basic deviation of G is a positive value, and the basic deviation of e, f, and g is a negative value. as the picture shows:
1. H is the common tolerance zone position for internal threads. It is generally not used as a surface coating or an extremely thin phosphating layer. The basic deviation of the G position is used for special occasions, such as thicker coatings, which are rarely used.
2, g is commonly used to plate 6-9um thin coating, such as the product drawing requirements of 6h bolts, the pre-plated thread uses a 6g tolerance band.
3, the thread fit is best combined into H / g, H / h or G / h, for bolts, nuts and other refined fastener threads, the standard is recommended to use 6H / 6g
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High Velocity Powder-Actuated Tool is used for normal concrete not harder than C40. The nail initial velocity is very high as there is no piston but high pressure gas to push it.
Powder-actuated tools come in high-velocity and low-velocity types. In high-velocity tools, the propellant charge acts directly on the fastener in a process similar to a firearm. ... Powder-actuated Fasteners are made of special heat-treated steel. Common nails are not used for powder-actuated fastenings.
High Velocity Powder-Actuated Tool
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