Explosive rivet
A snap rivet is a connector that is no longer used in aircraft and steel construction . It was developed in the mid-1930s by the engineer Karl Butter (1908–1997) who worked for Heinkel . He had been asked by his brother Otto Butter, an aircraft designer who had been working for Ernst Heinkel Flugzeugwerke since 1931, for help with the problem of riveting on construction parts that were only accessible from one side. He replied in a letter dated October 7, 1934, suggesting the explosive riveting process. From November 1, 1935, Karl Butter was employed by Heinkel - first as a freelancer, then one year later on a permanent basis.
Ernst Heinkel patented the snap rivet on December 1, 1936. The American companies DuPont and American Explosive Rivet Company in Baltimore acquired the rights to rent explosives in North America from Ernst Heinkel in 1939 .
Procedure
A cavity in the end of the rivet is filled with explosives . The rivet is inserted into the hole. Then it is heated with a gas burner or a hot piece of metal (soldering iron) attached, which causes the explosive charge to explode and the rivet to mushroom.
The advantage is that riveting points that are only accessible from one side can be connected (for example, fastening to pipes or closed square profiles). In addition, in contrast to the otherwise usual hollow rivets, the snap rivet allows liquid and gas-tight riveting.
The physical exertion of manual riveting of large rivet diameters is eliminated; the process is also more efficient, since the time-consuming shaping of the rivet head is no longer necessary and a second person is not required to counterhold.
Due to the general decline in riveting as a connecting means in steel construction compared to welding and screwing , the problems with handling explosives and the availability of other forms of blind rivets , the snap rivet is no longer in use.
Similar methods were tried out with water as a blowing agent, which was caused to evaporate suddenly by applying high voltage .
use
In the production of the Heinkel He 114 , explosive riveting was first used in series. During the Second World War , the process was also used for emergency repairs to combat aircraft, as it was possible to dispense with time-consuming dismantling.
Individual evidence
- ^ H. Dieter Köhler: Ernst Heinkel - pioneer of the high-speed aircraft. Bernard & Graefe Verlag, 1999, pp. 214-216.
- ↑ Holger Björgquist: Rostock Aviation History (s) Volume 4 - People and their places of work . Self-published by Förderkreis Luft- und Raumfahrt Mecklenburg-Vorpommern eV, 2012, p. 50.
- ↑ Reichspatentamt Pat. No. 666,878th website of the German Patent and Trademark Office. Retrieved October 22, 2014.
- ^ H. Dieter Köhler: Ernst Heinkel - pioneer of the high-speed aircraft. Bernard & Graefe Verlag, 1999, p. 216.
- ^ H. Dieter Köhler: Ernst Heinkel - pioneer of the high-speed aircraft. Bernard & Graefe Verlag, 1999, p. 215.