Hob is right to neuter the influence of tooth form symmetry
Time:
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source:BAGANZ CNC Machining
Graph 1 in gear cutting, gear hobbing teeth shape error is machined to sequel (especially shave tine is machined) precision and cutting tool life have bigger effect. The sort of gear hobbing teeth shape error and generation reason are more, mounting error of the graduation error of the error of tooth form horn of hob, machine tool, cutting tool all may cause teeth shape error. The article makes one analysis to the teeth shape error of neuter generation with respect to the hob when gear hobbing only. Gear hobbing process regard the gear that be cut and fictitious rack as the process that does not have backlash clench the teeth. When gear hobbing, the tooth form of end panel involute of gear includes sth resembling a net by the broken line with a few successive blame and become (like the graph 1 shows) , one included angle is formed between broken line and broken line, the acme of this included angle and the distance that form along involute normal direction between involute theoretically call arris to spend (pursue namely 1 medium DH, the DS in the graph forms the distance) between the broken line of involute to include sth resembling a net, DH is the principle error that arises necessarily when gear hobbing. The included angle acme that will form arris to spend rises with linear join, form the involute on end panel tooth form namely, every acme is corresponding on end panel horn of a tooth form, one is formed in facewidth direction linear. Hob is to neuter when showing hob installation is on arbor, hob random ages (or alveolar) the coincide degree of symmetrical axes and line of tine base center. In hob is being analysed to be opposite respectively below with incorrect in the impact of two kinds of conditions to teeth shape error. Fall to medium circumstance in hob (like the graph 2 show) , hob center line and coincide of line of tine base center, the M1 of point of tangency that hob ages groove controls two side edge and tine base, M2 controls semmetry, the nodical P1 of its path of contact is on the central line of hob and tine base. Right now, the point of tangency that forms arris to spend shows semmetry to distributing on tooth form of side of left and right sides of end panel of teeth of a cogwheel, the arris of correspondence of place of side of tooth profile left and right sides spends a worth DH is completely equal and symmetrical, end panel dentiform controls side (the broken line that includes to form tooth profile curve) complete also semmetry, corresponding DS value is identical also and show semmetry to distributing. From this knowable, the teeth shape error that forms right now also distributings symmetrically. The graph is shown 3 times reach each paragraphs of broken line for the tooth profile curve that in hob the circumstance in be opposite leaves condition of imitate gear hobbing to wrap subsidiary channels in the human body through which vital energy to form (the node of the each horizontal line in the graph and tooth profile curve is namely the broken line that makes tooth profile curve and. Graph 2 graphs 3 graphs 4 graphs 5 in hob incorrect below medium circumstance (show) 4 times like the graph, hob decides hard in the position on arbor, photograph of hob center line is met to line of tine base center deflection is certain angle, the M3 of point of tangency that hob ages groove controls two side edge and tine base, M4 shows semmetry to distributing no longer, staggered one paragraph is apart from however, the nodical P2 of its path of contact go up in line of tine base center and do not go up in hob center line, namely the node of edge and path of contact (namely cutting is nodded) relative to the asymmetry connecting a line at node and gear center line. Right now, the point of tangency that forms arris to spend shows asymmetry to distributing on side of left and right sides of end panel dentiform, the arris of place correspondence spends a worth both neither is equal also asymmetry. Apparent, end panel dentiform controls side (the broken line that includes to form tooth profile curve) all asymmetry. Each paragraphs of broken line that the graph shows institute of state of gear hobbing of the imitate below the circumstance in was opposite for hob namely 5 times to form. Although wrap the whole involute curve that subsidiary channels in the human body through which vital energy gives is semmetry finally, but each paragraphs of broken line that includes subsidiary channels in the human body through which vital energy to give involute curve and each acme position all asymmetry. Right now, the bit more corresponding tooth form horn on the tooth form of or so side that arris spends a place is unequal, the DS value that the arris of the correspondence of tooth form horn that each correspondence nods spends value and correspondence is not same also. From this knowable, the both neither of teeth shape error that forms right now is symmetrical, not identical also. By afore-mentioned analysises knowable, hob is affected to dentiform symmetry to neuter great. Asymmetry of the tooth form after gear hobbing ages the shave in bringing about shave tine process knife tooth controls side to get power inhomogenous, teeth shape error of treatment of tine of immediate impact shave and shave tine knife service life, still can reduce a machine tool to use precision. Accordingly, in gear (age less especially several gear) in gear hobbing treatment, should make sure hob is right as far as possible neuter. CNC Milling