Rivet nuts are a new generation of riveting fasteners on the market. It changes the traditional way of installing parts on thin plates, and is a new breakthrough in the joining process of plates. At present, in the sheet metal industry, the rivet nut fixed by riveting is generally used to fix the threaded connection nut on the sheet metal parts. There are two types of riveting methods and tooling. One is riveting with a riveting gun, which is mainly used for The riveting of sheet metal parts with small batches of various types and maintenance is mainly used; the other is the riveting of sheet metal stamping die, which is mainly used for riveting of single type of sheet metal parts in large quantities. Both of these two riveting methods have fatal defects - low consumption efficiency, high labor intensity and poor stability of riveting quality. Another riveting method is automatic riveting. This riveting method has simple operation steps and can just compensate for the above two methods.

1. Riveting method of riveting gun

The riveting steps of the riveting gun are: take the part → insert the nut → screw the riveting head into the nut → pull riveting → unscrew the nut with the riveting head → waste.

The defects of the riveting method of the riveting gun: the steps are cumbersome, the efficiency of manually inserting the nut is low, the production efficiency is low, the requirements for the skills of the employees are high, the service life of the riveting gun is short, and the service life of the riveting gun head is short.

2. Mold riveting method

Die riveting steps: take the part → insert the nut → position on the die → press riveting → waste.

Defects of die riveting method: cumbersome steps, low efficiency of manual nut insertion, low consumption efficiency, poor compatibility of fixed stroke riveting method with nut length deviation, and unstable riveting quality.

3. Automatic riveting plan design

Automatic plug-in equipment has been widely used in the sheet metal industry, and the technology has been quite mature, but because the riveting nut used by the automatic plug-in equipment is a pressure riveting nut, there is no precedent for using a rivet nut. Compared with pull riveting, pressure riveting still has the following defects:

(1) For riveting nuts of the same specification, the cost of the pressure riveting nut is higher than that of the riveting nut (at the market price).

(2) Pressure riveting has strict requirements on the thickness of the sheet (material thickness ≥ 1.0mm), so it is not suitable for parts that require the use of thin materials (material thickness < 1.0 nm). Thickness, it will greatly increase the cost of production. At the same time, the structural parameters of the pressure riveting nuts used in different plate thicknesses are not consistent. If the pressure riveting nuts are used for production, the types and specifications of nuts will increase, which will eventually lead to an increase in production management and quality management costs.

The aluminum rivet nuts used in the sheet metal industry are mostly hexagonal rivet nuts. At present, the general automatic plug-in equipment cannot be used for hexagonal rivet nuts for the time being. The main reason is that the automatic plug-in equipment cannot complete the directional transport of hexagonal rivet nuts. Replacing the hexagonal rivet nut with a cylindrical rivet nut can deal with the directional transport of the rivet nut. However, after the cylindrical rivet nut is riveted, there will be a hidden quality risk when the screw is rotated.

At present, the design principle of riveting connection structure used in the sheet metal industry is generally different in shape of the riveting hole and the riveting nut. To the round riveting nut hole and the round riveting nut, there will be a serious riveting quality problem. During the process of screwing the screw into the riveting nut, the nut will rotate, which will cause the parts to be unable to be assembled and fixed.

After analysis, if the hexagonal riveting nut hole is matched with the circular riveting nut, the riveting nut will have a part of the material flowing to the gap between the circular riveting nut and the hexagonal riveting nut hole during the riveting process, forming a hexagonal shape boss. The boss can have the effect of preventing the nut from turning.

Mold construction. The working process of the mold is as follows: ① The parts are positioned on the positioning pins to ensure the degree of the riveting surface of the parts; ② The upper mold presses the riveting nut into the cavity of the lower mold, and the positioning pin moves down with the pressing of the nut; ③ When the positioning pin contacts After fixing the seat, the nut wall is plastically deformed, and the deformed nut and the parts are tightly separated to achieve the riveting effect; ④ The upper die continues to descend, and the lower die shaft sleeve cooperates with the upper die to stop the deformation of the nut and apply pressure again, and the local data of the nut deformed part is destroyed. Press into the gap of the hexagonal riveting hole of the part to form a regular hexagonal structure to avoid the rotation of the nut;

The automatic riveting steps are: removing the parts → positioning on the mold → pressure riveting → waste, so: the implementation of the automatic pressure riveting plan for the riveting nut has solved the problems of low riveting efficiency and complicated and cumbersome operations in the production process. The implementation of this plan can solve the riveting bottleneck problem in the sheet metal processing industry.