What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The pull-out type positioning pin and the tie-suspended type positioning pin are in the form of a straight cylindrical shape. The pull-out locating pin is temporarily pulled out from the connected piece of the tooling, and it is in a loose state; the tail of the tie-suspended locating pin is connected with a tie such as iron wire or string to the connecting piece of the tooling. After the locating pin is pulled out, the tie Suspended on tooling. The main disadvantages of the two types of positioning pins are as follows: First, the suspension straps are easy to fall off after long-term wear, and the pull-out positioning pins of the same parts are not convenient for on-site storage and placement, and are usually placed on the nearby ground at will; All kinds of positioning pins are prone to position transfer, forgetting and losing, which affects the reset of the tooling and the subsequent manufacture and assembly of aircraft products.
The difference between high-strength bolt friction type and pressure-bearing type connection: High-strength bolt high-strength bolt connection is to clamp the plate of the connecting plate through a large tightening pre-pressure in the bolt rod, which is enough to generate a large friction force, thereby improving the connection. The integrity and stiffness of the bolt can be divided into two types: high-strength bolt friction type connection and high-strength bolt pressure type connection according to different design and force requirements when subjected to shear force. The essential difference between the two is that the limit state is different, although It is the same kind of bolt, but it is very different in terms of calculation method, requirements, and scope of application. In the shear design, the friction type connection of high-strength bolts is the limit state when the external shear force reaches the possible maximum friction force provided by the bolt tightening force between the contact surfaces of the plates, that is, the internal and external shear force of the connection is guaranteed not to exceed maximum friction. The plate will not undergo relative slip deformation (the original gap between the screw and the hole wall is always maintained), and the connected plate will be elastically stressed as a whole. In the design of shear resistance, the external shear force is allowed to exceed the maximum friction force in the high-strength bolt-bearing connection. At this time, relative slip deformation occurs between the connected plates until the bolt rod contacts the hole wall, and then the connection depends on the bolt rod. The shearing of the body and the bearing of the hole wall and the friction between the contact surfaces of the plates jointly transmit the force, and finally the shearing of the shaft or the bearing of the hole wall is regarded as the limit state of the connection shearing. In a word, friction type high-strength bolts and pressure-bearing high-strength bolts are actually the same type of bolts, but whether the design considers slippage. Friction type high-strength bolts can never slide, and the bolts do not bear shear force. Once slipped, the design is considered to reach a state of failure, which is technically mature; pressure-bearing high-strength bolts can slide, and the bolts also bear shear force, and the final damage is equivalent to ordinary Bolt failure (bolt shearing or steel plate crushing).
In the prior art, the electric screwdrivers in the automatic locking screw machines all adopt the suction method to absorb the screws. Such a structure is relatively complicated, and the design of the air circuit needs to be considered, and the phenomenon of material jamming is prone to occur, and it cannot be carried out due to the reason of the air circuit. Deep hole locking screws cause great trouble to users.
Stainless steel screws usually refer to steel screws that are resistant to corrosion by air, water, acids, alkali salts or other media. Stainless steel screws are generally not easy to rust and durable, and can be used in environmental protection equipment, medical equipment, communication equipment and other fields.
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