With AutoLISP programming dish tooth form of involute of form gear milling cutter

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Summary: Introduced to use the AutoLISP programming that embeds inside AutoCAD dish principle of dentiform of involute of form gear milling cutter and method, gave out to devise example. Graph dish of form gear milling cutter that 1 introduction plan shows form of cut of milling cutter of gear of 1 dish of form 1 times the structure is simple, use convenient, be used extensively at the small lot treatment of gear of medium, small modulus or make repairs and supply replacements. But because this is planted,design of dentiform of milling cutter involute and treatment exist bigger academic error, because this is machined gear precision is inferior. Dish method of design of dentiform of involute of form gear milling cutter is normally 6 ～ are chosen inside involute limits 20 are nodded, pass computation or the coordinate that check a watch to reach every are nodded, next ordinal join is nodded each, can reach approximate involute tooth form (inspection template also can design) by this method. Method of this kind of design is put in certain blemish, if take a place too little, design precision not tall; If take a place overmuch (far over at 20 o'clock) , calculate trival, and inconvenience of gotten approximate involute tooth form undertakes at using machine tool of high accuracy numerical control sequel is machined. For this, this literary grace designs the involute tooth form of milling cutter of form of turntable of tine of straight tine cylinder with the AutoLISP program that sets inside AutoCAD. This method can obtain the involute with academic taller precision, and CNC Machining of facilitating dentiform follow-up. The bit more aleatoric coordinate computation on 2 designs principle and methodological involute ages cylinder ages the tooth form of turntable form milling cutter is like a graph continuously 2 are shown. In the graph, curvilinear BD is involute, among them BA ministry dispenses is machined the involute tooth profile of gear is identical, AD part carries the involute of round above on the head for tine, it is the share that adds for milling cutter only, its take a value to have a few difference according to different design data. Can think the size of AD and gear modulus M are concerned, take Rd=ra+0 here.

2m. Set origin of the coordinate that be by treatment gear center, oy is alveolar and symmetrical line, in having Wx=wb+qx=wb+invax(1) type: Ax=arccos(rb/rx) Wb=w-inva by the graph 2 knowable: In W=(p-4xtana)/2z+s/mz(2) type: S -- reference circle transverse tooth thickness reduces small amount (take S=0) Z commonly -- tine counts M -- modulus X -- modification coeffication Rd.

R of the biggest round radius.

Ra of reference circle radius.

Tine carries round radius Rb on the head.

Rf of basic circle radius.

Rx of tine root round radius.

The aleatoric radius that nod a circle pursues tooth form of 2 milling cutter type (2) generation enters type (1) , can get Wx=(p-4xtana)/2z+invax-inva(3) accordingly, the coordinate that the radius on involute nods M for the random of Rx (Xg, yg) can beg a coordinate that nods each inside curvilinear BD part to be worth from this for {xg=rx Sinwxyg=rxcoswx(4) , these dots are the node on involute namely. Transfer tooth form of processing milling cutter is mixed by involute transfer curve (linear) composition. Because transfer,curvilinear part does not participate in clench the teeth, because this wants gear of not cloggy conjugate only (or rack) the movement that tine carries on the head, can be its design aleatoric curve or linear. Opposite crosses a curve (linear) the start that processing will decide program scale involute. This program involves the scale of involute part only, and transfer curvilinear part is handled artificially by sequel. Involute start can divide surely really for two kinds of circumstances: When Rf ≤ Rb, part of above of basic circle Rb is involute, the BC part under basic circle is transfer curve, because the start of this involute begins from Rb place, namely Ax=0 of tooth form horn. When Rf>rb, basic circle Rb is involute to the part of tine root round Rf. The part does not participate in clench the teeth under tine root round Rf, not was necessary to use involute, because the start of this involute begins from Rf place, namely Ax=af of tooth form horn. No matter afore-mentioned where are planted circumstance, the terminus of involute all is in place of Rd of the biggest round radius, right now Ax=ad of tooth form horn. Any curves all can use programming multistage music line segment (or straight line segment) the method that approach undertakes imitate, and line segment fractionize is more, principle error is smaller. This literary grace approachs a way point-blank with involute, use (Xg, yg) seeks solution formula, produce the node of aleatoric amount automatically by the AutoLISP program that sets inside AutoCAD, the involute that obtains aleatoric imitate precision thereby (this precision satisfies 8 class gear cutting precision can) ; Make the approximate involute rough sketch with very small error automatically with LINE command next (this outline is successive, in order to facilitate follow-up CAD/CAM CNC Machining) . Block diagram of program of graph 3 GEARTOOL GEARTOOL of this program entitle, its flow block diagram is shown 3 times like the graph (particular program summary) . 3 designs example although this program is developed on AutoCAD R14 platform, but involve commonly used order of AutoLISP commonly used function and AutoCAD only, because this can be on the AutoCAD of all sorts of version,move. Necessary setting should have to plot environment before moving, if the setting measures the decimal digit of the unit (default is 4) etc. When the design, want to input tine to count M of Z, modulus and modification coeffication X only, the process can make rough sketch of involute tooth form automatically. With 4 gear milling cutter (the design that treatment ages teeth of a cogwheel counts Z=21 ～ 25) is exemple, the program uses a method to be as follows: COMMAND: GEARTOOL Z: What the input machines gear to age several 21(press each knife date most denticulation counts) M: What the input machines gear modulus 2 X<0> : What the input machines gear modification coeffication, standard gear modification coeffication is 0 inputs after relevant parameter, the process makes the part of involute tooth form that the graph shows 4 times automatically. In this exemple, rf=0 of tine root round radius.

5m(z-2.

5)=18.

5mm, rb=0 of basic circle radius.

5mzcosa=19.

7335mm, attribute the situation of Rf<rb. The process gives the involute that does not have breakpoint and a symmetrical clue for start scale with basic circle Rb, the one aspect of the matter of symmetrical line machines gear center for place. Right now usable DIST command measures the interval between gear center and involute start, in order to examine the validity of Rb, if the distance between 2 o'clock is equal to value of computation of basic circle radius, show Rb is correct. Should notice: When the position that inputs a dot, should use take kind, and when taking involute starting point, need to use transparent order above all " ZOOM " undertake sufficient enlarge. In addition, before undertaking examining to Rb, cannot use " SCALE " the command undertakes shrinking putting, can make the distance between 2 o'clock produces change otherwise. Graph part of involute of 4 tooth form pursues after design of part of involute of tooth form of complete tooth form finishs 5 milling cutter, add by hand transfer curve, the milling cutter that if the graph is shown 5 times,gets namely is complete tooth form (dot of the C in the graph is tine root to cross bit of) ripely. When the design, should notice the following: Although relevant command can be joined to come true to make complete tooth form directly in the program, but such meetings make the program becomes very multifarious, be inferior to undertaking with handiwork sequel is handled more handy. When undertaking sequel is handled, the joint of line and line cannot be put in breakpoint. Because involute is comprised by cutty straight line segment, if need to undertake follow-up plot is operated, answer to undertake after sufficient enlarge. If ask to obtain taller involute tooth form to design precision, need to will be calculated only formulary Ax=ax+0.

The coefficient in 1p/180 0.

1 reduce can. CNC Milling CNC Machining