What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Screws are a kind of fasteners commonly used in daily life and industry. At present, in use, different types of screws are generally selected for fixing according to different screw lengths and other parameters. Since the screw length is fixed at the time of manufacture, when When using a large number of screws with different screw lengths, it is necessary to sort out screws with different screw lengths beforehand. This method is more troublesome, and sometimes in some special occasions, some screws with special lengths are required. Producing screws of this particular length individually is laborious and laborious.
Nuts are very common fasteners. Generally, the torque cannot be limited when the nut is twisted. The degree of tightness of the nut is mostly judged by the worker's experience. In this way, when the nut is over-tightened, it will lead to the destruction of the thread pair, thereby shortening the fastener. The life of the nut may even cause the bolts to be pulled off in severe cases; and the nut is too loosely screwed, which will lead to the problem of insecure fixing.
At present, during assembly of many pin installation mechanisms, the pins need to be installed into the holes or arranged in an orderly manner, and there are many problems in this assembly method. First of all, during assembly, if the hole diameter of the hole product is large, when the pin enters the hole of the hole product, part of the pin entering the hole of the hole product is not fixed, which often leads to slight deviation. In addition, this assembly method is usually only suitable for parts with large apertures and small depths, and when installing multiple pins, it is impossible to automatically install all pins in place due to space constraints. Special tools need to be made for installation operations, and it is easy to cause pins. damage.
There are two typical pin shearing fixture tooling, among which the traditional fixture shown in Fig. 1 is more complicated and consists of fixture, spacer, washer and shearing block guide post, hardened bushing, shearing block and so on. The cylindrical pin is installed in the hardened bushing, and the axial load is applied through the shear block to complete the shear test. The fixture is complicated in manufacture and has many consumables, because the size of the hardened bushing is similar to that of the cylindrical pin. , and to keep the notch of the cylindrical pin upward, it is difficult to install before the test, and the broken cylindrical pin after the test remains in the hardened bushing and is difficult to remove.
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