Service HotlineA nut is a commonly used fastener, usually combined with a screw to form a set of fastening devices. In order to effectively achieve a more effective tightening effect and prevent a single nut from loosening by itself, two nuts are used together in many places to further increase the tightening effect;
(1) The screw-in performance test is to screw the self-tapping locking screw sample into the test plate until one complete thread completely passes the test without breaking. (2) The destructive torque test is to clamp the stem of the self-tapping locking screw specimen in a thread mold or other device that matches the screw thread, and uses a calibrated torque-measuring device to measure the screw. Torque is applied until fracture, which should not occur in the clamped threaded portion. (3) Carry out a tensile test on the screw sample to check the minimum tensile load for failure. The fracture should be within the length of the rod or the unthreaded thread, and should not occur at the junction of the nail head and the rod. Before the sample breaks, it should be It can reach the minimum tensile load specified by the corresponding performance class. (4) Hydrogen embrittlement is a problem that must be strictly paid attention to in the surface treatment process of self-tapping locking screws. In the pickling process, the screw is stirred in dilute hydrochloric acid, and the amount of hydrogen absorbed by the pickling steel increases linearly with the square root of time and reaches the saturation value. Less than 100%, a large number of hydrogen atoms will be produced, which will be attached to the surface of the screw, resulting in hydrogen infiltration, and the steel will become brittle due to the absorption of hydrogen. The self-tapping locking screw takes 6~8h to drive hydrogen, and the temperature is 160~200℃ (phosphating) and 200~240℃ (electroplating). However, in the production process, the hydrogen drive time should be determined according to many production conditions such as core hardness, surface roughness, electroplating time, coating thickness, pickling time, and acid concentration. It is best to do it before passivation and just after electroplating.
screw is a tool that uses the physical and mathematical principles of the circular rotation and rotation of the oblique surface of an object to gradually fasten the mechanism of the utensil. A screw is a common term for fasteners, an everyday colloquial language. Screws are indispensable industrial necessities in daily life: tiny screws used in cameras, glasses, clocks, electronics, etc.; general screws in televisions, electrical products, musical instruments, furniture, etc.; as for engineering, construction, and bridges, large screws are used. Screws and nuts; transportation equipment, airplanes, trams, automobiles, etc. are used together with large and small screws. Screws have important tasks in industry. As long as there is industry on earth, the function of screws will always be important. The screw is a common invention in people's production and life for thousands of years. According to the application field, it is a great invention of human beings. At present, the head of the screw on the market is generally punched with a cross groove or a word groove, which is used for tightening or Remove the screw, but the cross slot or the slot is easy to deform after a long time, it is difficult to disassemble it with tools, and sometimes the tool of the corresponding size cannot be found and the disassembly cannot be carried out, and the disassembly is relatively inconvenient.
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).
Fasteners are a class of mechanical parts that are used for fastening connections and are widely used. It is used in a wide range of industries, including energy, electronics, electrical appliances, machinery, chemical industry, metallurgy, mold, hydraulic and other industries, in various machinery, equipment, vehicles, ships, railways, bridges, buildings, structures, tools, instruments, chemicals, instruments And supplies, etc., you can see all kinds of fasteners, which are widely used mechanical basic parts. In the fields of listed rails, construction machinery, etc., due to the harsh application environment, the requirements for fasteners are more stringent. If the fasteners are loosened, it may lead to serious consequences, resulting in a large amount of property damage, even serious life cost.
We have many years of experience in the production and sales of screws, nuts, flat washers, etc. The main products are: enlarged square washers, flat head flower screws, lock and female screws, nylon rubber rings and other products, we can provide you with products suitable for you fastener solutions.
