Method for fixing the position of a glass tube or glass rod spiral in a glass tube, glass tube assembly and the application of the same

摘要

The glass tube assembly has an outer glass tube provided with a tapered section and an inner glass tube or rod, which is arranged inside of the outer glass tube and which has a spiral section. The tapered section is formed by one or more projections on the inner surface of the outer glass tube. Each projection extends in a longitudinal direction of the outer glass tube and does not extend around its entire circumference. The internal width of the tapered section is smaller than the outside diameter of the spiral section of the inner glass tube or rod, so that the inner glass tube or rod is reliably prevented from slipping or rotating out of the outer glass tube by its spiral section. A method of making the glass tube assembly is also described.