Dongming fasteners are also known as standard products in the market. They are mechanical parts that can mechanically fix or bond more than two parts. Then, let's learn about the common problems and analysis of Dongming fasteners!
1. Tightening method of bolts and nuts
Threaded connections of bolts and nuts are the most common in fastener applications. Generally, self-locking nuts or redundant mechanical locks are used to prevent loosening to ensure connection strength. The installation of screw fasteners is also very simple, and it is enough to ensure enough torque to achieve the pre-tightening force of the interface, but many people do not know whether they should be tightened with the head of a nut or bolt.
Dongming fasteners can apply torque to the bolt head or nut to make it tightly connected. Under the following conditions of use, only one of the parts may be torqued.
1. The interference fit hole should be fitted with interference, and torque should be applied to the nut for installation.
2. When the shape and diameter of the bolt head and the nut are different, the shape and diameter of the bolt head and the nut are different (such as the square nut at the hexagon head bolt) or the diameter is obviously different, the torque should be applied to the side with the smaller load surface. For example, if the bolt head is smaller than the nut, torque must be applied to the bolt head. It is easy to understand if you exert force in small places, and exert force in large places.
3. When two different materials need to be fastened for different materials, the fastening force should be applied to the material with low friction coefficient. That is, tighten with torque on the side where the least friction is possible.
4. When the long bolt head is subjected to torque, it is very easy to have the problem of twisting and winding. In this case, applying torque to the nut helps to avoid this problem. There is such an application. The nut is a flanged nut, but not on the bolt head. That is, the friction radius on the nut side is larger than that on the bolt head side.
If the tightening torque is determined when tightening the nut, overloading may occur when tightening the bolt head with that torque. Generally, about half of the torque is necessary to overcome the frictional force on the tightening surface, so if the friction radius is small, more torque will enter the screw tightening part, and over tightening will occur. Vice versa, assuming that the torque is determined by the tightening of the bolt head, the torque is applied when the nut is tightened, i.e., the side with the larger friction radius, and the preload of the input screw tightening part is insufficient, which may cause loosening problems.
2. Why use gaskets?
Washers are a very common standard and are common in threaded connections like bolts and nuts. It can be said that washers are always used in combination with threaded fasteners such as bolts and screws.
1. When the base material is very soft, the surface of the base material of the base material will be damaged during the process of tightening the bolts and screws. Using the gasket, the pressing force can be distributed over a larger area, avoiding damage to the surface of the motherboard. , The substrate is very soft. When the periphery of the hole where the fastener is installed is damaged, sufficient force is often applied to pull the fastener toward the material motherboard during the process of screwing in the fastener. The existence of the gasket helps to generate Small coagulation pressure, so tensile failure problems may occur. If the surface of the motherboard to which the bolts or screws are screwed is smooth and uneven, the head of the fastener is likely to get stuck on it. With washers, the surfaces of bolts and screws will slip and installation becomes easy.
2. Some washers are designed with special structure and have the function of preventing nut from loosening. Commonly known as lock washers, there are many structural forms, such as open, star, wave and so on. Such lock washers must be used with nuts.
3. The role of Dongming fasteners
When tightening with bolts and nuts, it is necessary to apply torque with a torque tool or a hand wrench to lock. The torque is finally converted into the force required for the fastening part. A certain amount of force ensures the resistance of the joint to vibration relaxation and fatigue. In most APP applications, the higher the preload load, the better.
4. Application of Nuts
Nuts are common in structural assembly and are mostly used for forgings, castings, and mechanical parts, especially when threaded holes cannot provide enough thread shearing area, and the self-locking device cannot be used, the built-in nut is a very effective solution. Also, some large forgings and castings will drive the wire directly into the base part, which can be dangerous to the entire part if the screw breaks.
Through the above introduction, we have learned whether torque should be applied to the bolt head or the nut when tightening, the corresponding situation, the role of washers, the development of flange fasteners, and the method to ensure the required force for installation.
The above is the common problems and analysis of Dongming fasteners. If you want to know more, please feel free to contact us!