Press-press solder connection
A press-press-soldering connection (PV-PLV) is the combination of a press- fit connection and a press-soldering connection. A thin layer of solder is applied between the joining surfaces of the press connection, which increases the torque transmission capacity of the joint.
Press soldering
Press soldering is a special form of soldering and is one of the firmly bonded joints. In contrast to fusion soldering, the brazing material is not melted thermally. Particularly at the roughness peaks, where there is the smallest distance between the solder and the joining part, the atoms of the soldering material are brought closer to the base material by diffusion , which results in an increase in the integral part of the joint. The prerequisite for this is metallic contact between the surfaces. Aluminum , zinc or copper have proven to be suitable metallic contact layers . The filler material can be applied using various methods. This takes place primarily galvanically or via friction build-up soldering.
When Reibauftragslöten the brazing filler material is to be converted by the introduction of mechanical energy into the active region and by friction , heat and melted in the surface in a continuous movement coated .
Properties of a PV-PLV
The press-press-soldering connection is the combination of an elementary press -fit connection with a press-soldering connection. This can be achieved by coating one of the joining partners with a thin layer of solder that differs from the base material of the shaft and the hub . The result is a combined joint that has both non-positive and material-locking properties. The pressure required for the press connection means that local PV-PLV can build up. This results in an increase in the overall strength of the connection. The advantages of the force-fit press connections, such as simple production and good centering, are retained.
Advantages of a PV-PLV
- A major advantage of a PV-PLV is the high overall strength of the connection (with a zinc-coated PV-PLV, the connection strength can be 3 times that of a comparable press connection).
- Due to the less hard solder layer, the wear mechanisms that are known in press connections, e.g. B. fretting corrosion , greatly reduced. Thus, the separation and re- joining of the components possible without damage to the joint surfaces, as the less solid solder layer a breaking point represents.
- Press-press soldered connections are characterized by a greater power transmission , which, due to less installation space, allow smaller dimensions .
- With PV-PLV, larger manufacturing tolerances are possible, which can reduce manufacturing costs.
- There is no change in the chemical composition and no thermal deformation of the parts to be joined due to the welding heat.
- Press-press solder connections do not require any special constructive additives.
Manufacture of a PV-PLV
The production of a PV-PLV can be divided into three steps: generating the solder layer, joining the parts and the training process.
Generating the solder layer
The solder layer is by electrodeposition coating produced, thermal spraying or Reibauftragslöten of one or both parts to be joined. Zinc , copper or aluminum are particularly suitable as brazing materials , with zinc in particular achieving very good connection strength.
Put
The parts are joined by longitudinal or transverse pressing.
Longitudinal pressing
Longitudinal pressing is the axial joining of an inner part into an outer part. There is an excess between the two parts. This is done by forcing the shaft into the hub using mechanical or hydraulic devices. Compared to cross pressing, longitudinal pressing is the more economical process.
Cross pressing
Cross pressing refers to the pushing of a hub onto an oversized shaft. The joining process takes place by stretching the hub or cooling the shaft, i.e. by heating or cooling the parts to be joined. The heat treatment ensures that the excess is eliminated during the joining process. The choice between heating and cooling depends on the size of the part and the technical possibilities. When heating the hub, it is necessary to ensure that the temperature is not exceeded, otherwise structural changes in the material can occur (with steel around 200 to 400 ° C).
Work out
By means of a targeted energy input, the proportion of material connections created in the joint can be increased even after joining. This process is called training. This can take place in two ways: on the one hand mechanically by as much energy is introduced by a targeted rotation of the joining partners, that a diffusion of the applied solder takes place in the shaft and hub. Another option is electrical training. An attempt is made by applying a defined flow of current to bring so much heat into the joining zone that, as with mechanical training, the solder diffuses.
literature
- Istvan Lipóth: Transferability of the press-press soldering connection under torsional load, 1st edition, web-Univ.-VerlAG, Dresden 2003, ISBN 3935712774
- Klaus Wittke, Uwe Füssel: Use of local press soldered connections to increase the load-bearing capacity of press connections, ZIS Mitteilungen, Halle 1983
- Michael Schnick, Uwe Füssel, Heinrich Tersch: FVA research project no.390, increasing the torque transfer capability in torsion and circumferential bending through press-press soldering, FVA - final report, Dresden / Darmstadt 2005
- Michal Pejko: Considerations of the availability of press-press soldering connections, 1st edition, TUDpress Verlag der Wissenschaften Dresden, Dresden 2010, ISBN 3941298666
- Ralph Beetz: Multifunctional joints - constructive and technological investigations, web-Univ.-VerlAG, Dresden 2001, ISBN 3935712618
- Uwe Füssel: Application of pressure soldering for the production of combined joints, 1st edition, Karl-Marx-Stadt 1984
- Uwe Füssel: Combined Joins, Habilitation, TU Chemnitz, Chemnitz 1989
- Uwe Füssel, Heinrich Tersch, Istvan Lipóth: Connection and damage mechanism as a prerequisite for predicting the strength behavior of press-press-soldering joints and developing a calculation model, FKM, Frankfurt 1999, lit. Report no .: BMWi / AIF no. 10851 B / 2