Device for permanent joining of tubes

DETAILED DESCRIPTION I claim: 1.
A device for permanent joining of tubes (1, 2) made of flexible materials for use as covering or lining tubes when drilling holes in the ground, the device including a female portion (3) on a first tube (1) and a male portion (10) interacting therewith on a second tube (2), the male portion being provided with annular projections (11a-1) and recesses (12a-1) round its outer circumference and the female portion being provided with annular projections (4a-1) and recesses (11a-1) around its inner circumference, which projections during radial deformation thereof are arranged to pass each other and to be inserted said in annular recesses, the annular projections (11a-1) of the male portion (10) and female portion being flexible and axially spaced, and the recesses (5a-1) of the female portion (3) and male portion being spaced at a distance from each other corresponding to the distance between said projections and in which, in the joining position, the projections of the male portion (10) are inserted with, the projections (11a-1, 4a-1) and the recesses (12a-1, 5a-1) of the male portion (10) and the female portion (3) forming in cross section, a saw-tooth pattern, where each projection has two intersecting surfaces, of which a first surface forms an acute angle (.
beta.
) with the radial plane and a second surface forms an acute angle (.
alpha.
) with the axial plane, characterized in that, in the joining position, the male portion (10) continuously presses the female portion (3) radially outwards under deformation of at least one of the male and female portions, in that at least some of the projections (4a-1), (11a-1) of at least one of the male portion (10) and the female portion (3) each have a diameter which results in interference engagement between said projections and recesses (12a-1) (5a-1) of the at least one of the female portion (3) and the male portion (10) thereby producing said deformation and also serving for transmitting axial and torsional forces therebetween, and in, both the male portion (10) as well as the female portion (3), said first surface is situated on that side of a diametrical plane through said surfaces' intersection which is opposite to the respective portion's free end