The research that the blade of hob of scrape of hard alloy gear grinds

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The use of hob of scrape of hard alloy gear, already 30 years, but, grind to the blade of cutting tool, have the treatise of a lot of really. The method that article chapter grinds from blade is waited a moment, gave out accurate treatise, give out hereby. One, the structure of hob of scrape of hard alloy gear can see hob of scrape of gear of this hard alloy by the graph before there is E of an eccentric throw between blade face and its axes. At that time before horn of tooth form of left and right sides of blade face dentiform also because of cutting tool before the eccentric throw of blade face and produced very big change. If pursue (tooth form pursues) . Only (horn of tooth form of left reference circle) the line that this line is the tooth form part that we say normally, in fact this is inaccurate. The angle of this line, it is the point of view that the formulary place below describes. Tan(w is right) =(tan(an)*cos(wf)+sin (yf)*sin(wf))/cos(yf) Tan(w is left) the helix angle of hob of Yf- of the horn before the reference circle of the hob of Wf- of An- pressure angle in =(tan(an)*cos(wf)-sin (yf)*sin(wf))/cos(yf) formula (graph S) flute profile graph is seen by the graph, of this kind of hob normally tooth form horn is to point to horn of reference circle tooth form (be like horn of tooth form of left reference circle) . To the tooth form of hob, it is the left tooth form in pointing to a graph (on the right side of tooth form) will tell. It is a curve. This curve gets of hob before the drive of the parameter equation X=t/2/pi*(arcsin(e/rx)+-(sqr(rx^2-ro^2))/ro-+arcos(ro/rx) Y=sqr(ro^2-e^2) of blade face point, that is to say, this curve is reasonable talk what go up even if be described by this equation. Double operation symbol, use at dextral hob in front on the right side of, the left left hob coming back that is used at dextral hob from the back conversely the reference circle helix angle of hob of Ro=m/(2*tan(wo)cos(af)) Wo=arccos(cos(an)*cos(af)) An- but. Eccentric throw of face of the blade before the Rx- of basic circle helix angle of the hob of Wo- of basic circle radius of Ro- involute hob calculates those who nod radius E- hob is told conversely, if had known before blade face dentiform the coordinate of the dot, adopt the foregone requirement of hob, can calculate certainly give hob corresponding before the corresponding parameter with the other perhaps eccentric throw of blade face. This kind of cutting tool still is put in horn of another tooth form, if pursue left of tooth form horn mix point-blank on the right side of of tooth form horn linear (the dotted line in seeing tooth form pursues) . This curve, there is not formulary computation now. The X coordinate cost that can manage according to the tine top of hob only and the X coordinate cost that tine root manages come calculative. Nextpage hob blade grinds a graph by (hob blade Mo pursues) know with the making place of hob, the cam that shovel a back is same, accordingly, OK on the graph the included angle between the very easy included angle that sees tine carries circle and tine top shovel on the head to carry a curve on the back and tine root circle and curve of back of tine root shovel. And apparent different, the included angle that tine carries on the head (the horn after tine supports) the included angle of the apparent root that compare tine (the horn after tine root) small. The computational formula Tan of the horn after supporting by tine (W) of cam of K= of the horn after the W- in =k*z/pi/de type calculates those who nod the circle of the place appreciate (the quantity that shovel a back) the chamfer of Z- hob counts Pi=3.

1415926 know, the circle that nods when computation (De) when the diameter changes, its are corresponding hind horn also is different (graph R) hob blade grinds sketch map to grind sketch map to see by hob blade, when hob before blade face blade grinds those who pursue medium " after blade is ground before blade face " this line when, the part carrying blade on the head of new cutting tool arrived A dot, the position of tine root arrived the place that B chooses when, the 2*de that the external diameter Da= of the hob that has ground newly pursues medium (graph A) after hob blade is ground before the coordinate that takes A dot and B to nod is begged to be shown by graph R place below graph of blade face point, age the very width that grinds is U1, of tine root grind width U2.

We know the role after Nextpage1 calculates what hob side shovels a face, after the circumferential chamfer number of the hob of external diameter Z- of the De- hob that the capacity shovelling a back of hob states with K value K=de*pi*tan(13)/z formula is medium gets shovelling back the K of the quantity when us, formula of Ww of the horn after the side edge of hob is as follows: Tan (Ww) =z*k*sin (Am) / (Pi*dx) the tooth form horn that the Am in type is hob, in actual computation, had better use (graph S) the numeric computation of horn of medium or so tooth form. Dx is the formula above basis of computational dot radius, can know, the diameter that the computation of the Am of tooth form horn of Ww of the horn after the side edge of hob and hob and hob nods is concerned. Am is bigger, ww is bigger, dx is bigger, the tine top of face of the blade before Ww jumps over small foregone hob grinds quantity U1 and tine root to grind quantity U2, the top that try a tooth-like part of anything decreases grain Q1 and tine root to decrease grain Q2.

The decrement Q2 of the decrement Q1 that computational tine carries on the head and tine root can be calculated according to the formula of the face the root round diameter that the Dg in Q1=k*u1/(pi*de) Q2=k*u2/(pi*dg) type is hob if each sectional transverse tooth thickness need computational dentiform to weigh the word of Mo, must decide the transverse tooth thickness of corresponding hob. If pursue (graph B) be shown. (graph B) grind principle place to know according to the shovel of hob, be in same it is equal that the shovel grinds on-line tooth transverse tooth thickness. According to this one regulation, can calculate those who give the transverse tooth thickness of corresponding hob to assure dot and corresponding tooth depth. One up-to-date, the computational condition that the blade of hob of scrape of hard alloy gear grinds the horn before losing gradually all ready, when using these conditions, the tooth form part that difference will control is clear about respectively go. From the analysis above, can see, if hob according to before the parallel of blade face grinds a way, of the tooth form horn of face of the blade before can assuring changeless, but, this yes before the eccentric throw of blade face been decreasinging. A. Set, will before blade face blade grinds N second, made eccentric throw =0, the horn of or so tooth form that is hob only is changeless still, with controlling tooth form horn to differ big case looks, (M18) , 19 ° left and right sides is on the right side of its, left it is 13 ° left and right sides. According to the common sense of gear hob, the eccentric throw =0 when hob when, the part of or so tooth form of the hob of hob approachs 20 ° , very apparent, this kind grinds a way cannot be used. B. If the blade of hob is ground,use change of eccentric throw grind a way, need the numeric Q1 with corresponding computation, the coordinate of face of the blade before the hob with Q2 new ground, computation gives corresponding eccentric throw, although use the equation of X and Y, computation gives corresponding eccentric throw. Next, the actual eccentric throw that grinds according to present blade has consideration new now eccentric throw, computation gives coordinate of corresponding hob tooth form, undertake comparative, find metabolic numerical value the smallest, will decide the method that blade grinds. Calculate respectively according to or so tooth form with respect to need so ability decision. Pass the analysis of above, can roughly the partial principle that the blade of hob of the horn before the specification is lost grinds and the method that should use. Actually, want to alternate slightly only, can solve before the blade of hob of the horn before the method that the blade of horny hob grinds and zero grinds a method. As a result of,be only length be caused by, these detailed calculative heavy and complicated, renew in the future. This one comes here end. CNC Milling