Abstract: A self-tapping screw (10, 30) comprising a drive (12) and a shank (14) bearing a thread comprising a main thread (16, 32), wherein the main thread (16, 32) has a maximum main thread external diameter (DAF) and a cutting area (F) and a supporting area (T) following in the direction of the drive (12), wherein the shank (14) has a threaded end (18) at an end opposite the drive (12), with the screw end (18) having a diameter (DE) of at least 20% of the maximum main thread external diameter (DAF), The shank further has, in the region of the screw end (18), a tap flute (20), wherein the tap flute (20) comprises at least two tapping thread turns (20a, 20b, 20c) which attain, in their external diameter (DAA), no more than 90% of the maximum main thread external diameter (DAF) and form a tap region in which the tapping thread turns (20a, 20b, 20c) have the same diameter development, and in addition in that the diameter of the main thread (16, 32) in the tap flute region (AB) is less than or equal to the diameter (DAA)

Abstract: The invention relates to a screw (IO) in order to cut a mating thread in a plastic article, comprising a lower threaded part (F) and an upper threaded part (T), the lower threaded part having a larger diameter and its tip covering a larger surface than the upper threaded part.

Abstract: A self-tapping screw (10, 30) comprising a drive (12) and a shank (14) bearing a thread comprising a main thread (16, 32), wherein the main thread (16, 32) has a maximum main thread external diameter (DAF) and a cutting area (F) and a supporting area (T) following in the direction of the drive (12), wherein the shank (14) has a threaded end (18) at an end opposite the drive (12), with the screw end (18) having a diameter (DE) of at least 20% of the maximum main thread external diameter (DAF), The shank further has, in the region of the screw end (18), a tap flute (20), wherein the tap flute (20) comprises at least two tapping thread turns (20a, 20b, 20c) which attain, in their external diameter (DAA), no more than 90% of the maximum main thread external diameter (DAF) and form a tap region in which the tapping thread turns (20a, 20b, 20c) have the same diameter development, and in addition in that the diameter of the main thread (16, 32) in the tap flute region (AB) is less than or equal to the diameter (DAA)

Abstract: The thickness of the fingers of the line is modified, while the pitch of the fingers is kept constant, so that the capacitance between two successive fingers varies substantially proportionally to the product P.sub.HF .times.dI/dx, in which P.sub.HF represents the microwave power at any point x in the line and dI/dx the gradient, as a function of the position x on the line, of the current I delivered by the voltage supply creating a continuous electrical field E.sub.o between the electrodes of the tube. The values of P.sub.HF and of I are measured on the tube having a constant coupling resistance or are calculated by a computer program.