Каталог Dormer Pramet фрезерование 2021 - 2022 - страница 770

9 WORKING CONDITION WHEN MILLING As stated above, chip thickness h changes during a single revolution thickness hm is dependent on the type of milling cutter and on en- depending on the angle j in line with the formula hj = fz × sinj. gagement conditions, particularly the ratio of ae/DC, feed per tooth Maximum chip thickness with steady fz is reached within the axis of fz and naturally also on the entering angle KAPR – kr. The following the milling cutter. The average thickness of a chip (hm) removed by figure shows illustrative examples. one tooth during one revolution is calculated as the height of a rec- tangle with the same area as the area under a sine curve relative to the radial depth of cut ae . Average chip a b c d e hj h j = f z .sin j hj h j = f z .sin j hj h j = f z .sin j hj h j = f z .sin j hj h j = f z .sin j hm hm hm hm hm fz fz fz fz fz hm = 0,64 . fz hm hm hm hm hm h1 = 0 h2 = 0 h'1 > 0 h'2 > 0 h'‚1 > 0 h''2 = 0 h'1 > 0 h'2 > 0 h''1 > 0 h''2 = 0 h max = f z h max = f z h max = f z hmax= fz fz vf vf vf f vf vf j j f j j DC f j DC vc vc vc vc vc DC DC DC a e= DC ae m ae ae ae Average chip thickness hm for milling (with the centre) in accordance with figure a, b, d is calculated based on the formula: ae hm = fz . sin kr 57.3 ae DC . arcsin . DC Average chip thickness hm for machining with the side of the milling cutter (figure c, e) is calculated based on the formula: ae hm = fz . sin kr . 114.6 . 2ae DC . arccos . 1- DC For milling with the side of the cutter in line with figure e, where the ae/DC ratio is very low < (0.2), average chip thickness hm can be calculated using the simplified formula: ae hm = fz sin kr DC Where: hm Is average chip thickness [mm] fz Feed per tooth [mm/tooth] ae Radial depth of cut [mm] DC Diameter of the milling cutter [mm] kr Entering angle of the main cutting edge (KAPR) [°] 769