TOX without riveting in body application analysis

With the development of the car and the requirements of the environment, the pursuit of lightweight body, the limitation of fuel consumption, more and more all-aluminum body has come to everyone's field of vision, and for all-aluminum body, there are relatively few applications without riveting connection. .

First, the introduction of TOX process

Through a special non-rive joint mold, under the action of external force, the combined material combination is forced to produce material flow at the joint point, forming a joint process of plastic deformation, called no-rive joint, which is abbreviated as TOX or Clinching. It is a non-removable point connection technology for plastic sheets.

Riveted riveting application diagram

No riveting application details

Riveted section

Tox connection step-by-step diagram

Second, the process

No riveting has a certain tensile strength and shear strength. Compared with spot welding, the cost can be saved by about 30%, no connection deformation, static connection strength is about 70% of spot welding, dynamic fatigue strength is higher than spot welding, and the process has five stages.

1. Initial press-in: At this stage, under the action of the pressing force of the punch, the upper and lower sheets are mainly elastic deformation, accompanied by a small amount of plastic deformation.

2. Initial forming stage: At this stage, from the beginning to the end, as the punch goes down. The upper and lower sheets are restrained by the push rod, the concave mold and the convex mold, and the upper contour is formed by the combined action of the elastic plastic deformation.

In the initial forming stage, the tissue at the rounded corner of the dot is pressed by the punch and the die, the lattice is compressed, and the structure is strengthened. At the same time, at the annular groove formed by the die and the push rod, since the material is unconstrained, the material can be freely stretched, so that the rest of the crystal lattice of the material hardly changes, which is favorable for the preliminary formation of the dot and is in the plastic forming stage. Material deformation leaves room.

The sheet is similar in the initial press-in stage and the initial forming stage to ordinary stamping. The difference is that in the initial stage of formation, only the lattice of the round neck is compressed, and the structure is strengthened to form the upper part of the rivet joint. profile.

3. Plastic forming stage: At this stage, since the dot forms an upper contour in the initial forming stage, the material is prevented from flowing upward, so that it can flow only toward the annular groove and the side of the die in the direction of "minimum resistance".

The material first flows to the annular groove under the action of the pressing force to fill the annular groove; as the annular groove is gradually filled, the resistance to the annular groove gradually increases, and the material in the upper sheet flows toward the die. When the resistance of the side is smaller than that of the annular groove, the material in the upper sheet starts to simultaneously squeeze the side of the lower sheet until the punch reaches the dead point, and the dot is completely formed to form a dot similar to the riveting, thereby achieving riveting. the goal of.

4. Pressure- holding stage: The mold continues to maintain pressure for a certain period of time, which can fully fill, nest and completely shape the material, and achieve the effect of preventing roundback rebound. The quality control of the pressure holding stage directly affects the level of product qualification.

5. Back pressure stage: The riveting connection is usually used for the housing connection of the outer surface of the product. It is not desirable to have a convex point on the connecting point. Therefore, it is necessary to back-punch the dot once and press the protrusion back. In the case of back pressure, the die is a flat anvil, and the punch is a cylindrical punch.

Third, TOX connection and spot welding comparison

Fourth, TOX connection structure

Stamped dot connection double point connection

Miniature point connection SKB dot connection

SKB flat point connection riveted dot connection

Vario type dot connection

Stamped dot connections create a joint without edges and burrs that do not affect the corrosion resistance of the panel.

The double-point connection prevents the connected workpieces from rotating relative to each other, and the connection strength is significantly increased compared with the single-point connection, and is particularly suitable for connecting the narrow flange surface plates and the limited installation space.

The micro point connection point is only 1.5-2mm. It can be connected to sheet metal with a thickness of 0.1-0.5mm.

The SKB dot connection is formed by a special concave die consisting of a fixed part and a moving part with 4-6 movable mold lobes. The fixed part ensures accurate centering to form a joint point, and the movable part guides and constrains the material of the joint point plate material. Flow forming.

The biggest feature of SKB flat-point connections is that the other side is flat, because the bulge has an impact on the actual design and production. In the first step, the general tox connection dot is first processed, and the second sequence is used to press the convex portion back to form a flat point (±0.1 mm). The original high shear tensile strength of the connection point remains unchanged.

The riveted dot connection is characterized by the extrusion of a simple cylindrical rivet into the joining of two layers of the board without tearing and shearing, forming a high-strength joint.

Vario-type dot connections are used for excessive thickness differences, non-deformable materials and deformable materials, and the connection between metal and non-metal. The side plates of the die are pre-punched to withstand radial and axial forces. Multiple points are connected at the same time, and the workpiece needs to be accurately positioned.

In the riveting process, the deformation of the material is achieved by the mold to achieve the connection, but what if the punch is caught in the aluminum material and cannot be pulled out?

A layer of lubricant can be applied to the mold to solve the problem of mold sticking. There is also a method of spraying with 50/50 water and alcohol. The advantage of this method is that it does not affect the subsequent coloring process. The third method is to use special shapes. The mold is polished as needed.

V. Conclusion

Because of the connection strength limit of tox, it is mainly used in the door, cover, trunk and door opening. It also increases the difficulty of the sealing of the sealing strip, but the tox is cold deformation, not limited by materials, in steel and aluminum mixing. The body and some high-end cars are used more and have a greater role in actual production and design. (Part of the material in this article was taken from Tokes Stamping Equipment Co., Ltd.)

Brief introduction

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