SE7705045L - GENGTAPP - Google Patents

Abstract

There are taps with progressive-cut effect which have a thread-cutting part (1) over whose entire length grooving extends which comprises a flute (5) which rises at an angle to the rear without bends from the first thread turn and has a rake face inclined relative to the tap centre line (8) in such a way that forming chips are directed towards the front or in the feed direction. In such a tap, grooving extending without bends over the entire threaded part (1) and permitting an oil feed is convenient independently of the setting angle ss, which is important for the progressive-cut effect, the directing of the chips towards the front and the size of the chip space formed by the flute. Favourable grooving exists if the flute (5) extends over the entire thread-cutting part (1) up to the last thread turn and the number n of thread turns is proportioned in such a way that the depth of the flute at the last thread turn is 0.1 to 2 times the thread depth t, and the following dependency on the number n of thread turns is maintained for the flank clearance angle alpha o and the pitch-diameter taper quotient qd2: <IMAGE> where K is a material constant. Here, thread guide teeth lying behind the threaded part are omitted as far as possible, and the guidance features of the tap are improved by optimising the variables alpha o and qd2 Vin the requisite manner. <IMAGE>