Design of industrial structure connectors products: weld nuts, you choose the right?

Design of industrial structure connectors products: weld nuts, you choose the right?

A Weld nut is a nut outside the nut suitable for welding, generally, weldable material made of thicker material ideal for welding; welding is equivalent to the two separate parts into a whole, with high-temperature melted metal mixed and then cooled; the middle will be added to the alloy, the internal is the role of molecular forces, the strength of the general than the parent strength. The welding parameters' experimentation depends on the weld's fusion size, according to the fusion size adjustment of welding parameters, until defects are eliminated. Of course, welding quality is related to the pre-welding treatment, ash removal, oil stains, etc.

Is the material of the welded workpiece (the same or different), by heating or pressurizing or both, and with or without filler material, so that the material of the workpiece achieves the inter-atomic construction and the formation of a permanent connection of the process, welding nut is a fastener with internal threads and used in conjunction with the bolt. Welding nuts are fasteners with internal threads and are used with bolts to transmit motion or power. German Standard (DIN), British Standard (BS), Japanese Standard (JB).

Many automobile designs use sheet metal structure parts, so weld nuts are widely used in automobiles.

Welded nuts are used relatively little in other industries, where different sectors can use thicker steel plate designs that can be directly machined into the form of internally threaded holes. This is because the welded nut is widely used in the automotive industry. However, the relevant national standards and automotive industry standards on the definition of the welded nut are not perfect or very appropriate. Hence, people often design field assemblies when there is such a problem, especially when the threads appear slippery and teeth frequently occur.

The primary standards of weld nuts are Weld Square Nuts, Weld Hexagon Nuts, Hexagon Weld Nuts For Fixing The Safety Belt Devices Of Vehicle, Weld Round Nuts, Weld Hexagon Flange Lock Nuts, Weld Hexagon Flange Nuts (Weld Flange Surface Nuts), T-type Weld Nuts, etc. The standards are standardized, and the standard numbers are DIN928, DIN929, Q369, Q368, DIN EN ISO 21670, DIN977, JISB1196, etc.

1. Design time needs to pay attention to some of the standard load requirements for welding nuts and the corresponding level of welding nuts to ensure that the load requirements differ. The eight levels of nuts ensure that the load requirements are also low, not to mention using bolts with 10.9 levels of matching.

For example, the welding square nut standard DIN928 is commonly used to design the welding square nut selection model. M10 welding nut specifications, for example, the standard guaranteed load requirement is 44.8KN, and GB/T3098.2 standard level 8 nut guaranteed load requirements is 50.5KN, so the standard requirements of the welding nut are between the standard nut guaranteed load of 6 and 8 level nuts.

We look at the GB/T3098.1 standard 8.8 bolt minimum pull-off load requirement of 46.4 KN. It can be seen that the standard requirements of the guaranteed load of the welded nut and 8.8 bolts to match are prone to problems, not to mention matching with the 10.9 level of bolts.

This design was barely acceptable in the previous primary torque method of tightening, but now the automotive industry uses the torque angle method of tightening to yield the above. Even with the 8.8 level of bolts, the bolt's axial force will match to reach the minimum breaking load, so the weld nut sliding teeth will be tightened. If you need help finding a JIS B 1200 flange welding nuts style that meets your requirements, contact our customer service team at adelajonly@gmail.com or www.juxinfasteners.com.

In addition, there is a situation that needs to be addressed: welded nuts are currently cold upsetting out of the general cold upsetting will appear cold deformation strengthens the problem, but, after welding, often due to welding heat input will reduce the strength of the welded nut to a certain extent, so that the welded nut welded strength will be reduced some of the guaranteed load will be reduced so that the welded guaranteed load will be challenging to reach the required guaranteed load Requirements.

Strength will be reduced after welding. This is just a theoretical analysis; there is no support for test data. I hope the conditions of the peer to analyze or have been tested, the relevant data to share to see the actual results, and the theoretical analysis are consistent.

Some people will ask questions: we are by this standard to develop why no problems occur. This point does not be complacent; first of all, the use of the torque method of tightening relatively low preload, by the current standard, ensures that the load strength requirements can guarantee that there will be no slippage of teeth if you use the torque angle method of tightening will require special attention.

2. Another aspect is that although you are by the standard requirements for the development, if the supplier level is higher or you have experience in this area, it will generally increase a tempering heat treatment process, so that is the same weld nut thickness case, the guaranteed load can reach the standard guaranteed load requirements of the average nut of class 10, so there is no problem in the loading process.

For JIS B 1200 flange welding, the nut standard load has installed the corresponding GB/T3098.2 standard typical nut load requirements. Also, due to the DIN977 flange face weld nut contact surface being more significant, in the torque corner method of tightening, or the connected parts of the material strength are relatively low in the case, will not produce pressure collapse behavior, so it can preferred DIN977 flange face weld nut.

There are also recommended the preferred choice of flange face weld nut is because the DIN928 weld square nut has four convex welding points, and the DIN977 flange face weld nut has three convex welding points so that the three points form a flat surface in the welding more likely to ensure that the parallelism of the welded requirements. For example, the M10 flange welding nut ensures the load is 60.3 KN, consistent with the standard gb/t3098.2 requirements. It should be noted that the height of the DIN977 flange welding nut is about 1.3 times the nominal diameter of the thread if you change from the welding square nut into a flange welding nut when you need to pay attention to the length of the bolt changes.

To summarize, the design principle of matching bolts and nuts is that the strength of the nut at least requires the same performance level of the bolt to match; you can ask for a higher level of the nut to match the lower level of the bolt to ensure that the assembly will not slip teeth. For example, a grade 8 nut can match the highest bolt, which is 8.8 grade.

In addition, it is necessary to emphasize that the use of ISO7044, all-metal lock nuts, and other designs, generally required to match with the same grade of bolts, is not recommended to reduce the level of the requirements of the design. For example, ten 10-grade DIN6927 all-metal lock nuts should not be used with 8.8-grade bolts.

It is easier to find the bolt and nut matching design requirements because the bolt fracture is sudden. Bolts, nuts, and thread slippage are likely to occur slowly and not easy to find, so the common failure form of the bolt and nut connection, bolt fracture, bolt thread slippage, nut thread slippage, we design when we hope or requirements of the failure form of the occurrence of the possibility of over-tightening of the case, the bolt We hope or require the failure form to occur in the design is that in the case of possible overtightening, the failure form of the bolt is the fracture failure of the bolt, but not the slippery teeth of the bolt and nut failure. The above is an introduction to the design of bolts and nuts when the matching problem occurs; there are other technology-related professional issues we can contact to discuss; email:adelajonly@gmail.com；www.juxinfasteners.com.