α = normal pressure angle α = apparent pressure angle Tooth thickness measurement and pitch inspection

Transcription

1 Tth thickess measuemet ad pitch ispecti Tth thickess measuemet Whe yu eshape a shavig cutte yu educe the chdal thickess f the teeth f a value icluded etwee 0.06 ad 0.10 mm. I fucti f this value yu have t educe the cutte utside diamete accdigly, i de t maitai the eve ctacts cditis. F this pupse, each cutte is always accmpaied y a eshapeig diagam that defies the cespdece etwee tth thickess ad utside diamete. The thickess measuemet f each tth is t vey cmftale, ad f this eas it is me cmm t measue, with a plate micmete the W size teeth as idicated i figue N 1. Fig.N 1- pa measuemet W me teeth with plates micmete Thee is a uite pecise elatiship etwee value ad value W. Csideig the fllwig symls ad makig efeece t figue N 1, yu have the elw stated elatiships: = tth chdal thickess = mal chdal thickess l = space width pitch diamete d = pitch diamete = pitch adius h = addedum m = mdule m = mal mdule d g = ase cicle diamete t g = ase pitch α = pessue agle α = mal pessue agle α = appaet pessue agle s β = ase helix agle x = pfile shift fact

2 δ ad = d 2 = d se δ 2 f spu geas: W = m csα 1 ( Z ) m Z ivα 2 x m seα The ume f teeth t csideed f the measuemet Z ca e calculated with: α Z = 180 0,5 Z (with α i degees) F helical geas yu have : W = m csα ( Z 1) m Z ivα s 2 x m seα 0 eig Z α s tgα s tg = Z β 0,5 metimes it is t pssile t cay ut this measue ecause thee is chace f the tw micmete plates t tuch the flaks f the geas i the same time; see figue N 2. The cditi that is euied t e ale t cay ut the measuemet is W se β M cs β Fig.N 2- metime yu cat measue spa measuemet W me teeth with plates micmete

3 If this is t pssile it will e ecessay t pefm the size ve lles measuemet. With efeece t figue N 3 yu ca have 4 cases: Fig.N 3- Measue f size Q lles eve ume f teeth dd e 1)- pu Teeth with Z = eve ume: d l ivα = ivα fm which yu tai 2 csα 2 csα = ad the csα 2)- pu Teeth with Z = dd ume with α ad values taied fm the pevius fmulae yu calculate: Q = 2 cs d 2 Z 3)- Helical Teeth with Z = eve ume: d ls ivα = ivα s 2 cs β cs α 2 s csα csα s = fm which Q = 2 s Q = 2 d d s 4)- Helical Teeth with Z = dd ume: with α ad values taied fm the pevius fmulae yu calculate: Q = 2 cs d 2 Z But this measuemet t is t easy t make, csideig the uite ig value f Q that wuld make ecessay the use f lage ad awkwad micmetes. Quite fte, the it is pefeale t cay ut the measuemet etwee e lle ad the clsest e wall as idicated i figue N 4. α

4 F pu Teeth : Q1 = f F Helical Teeth: Q = 1 Fig.N 4- Measue f size Q 1 etwee e ad lles f The Q 1 ad W values ae mally idicated i the eshapeig diagam. Pitch ad ecceticity e ispecti The ispecti f the mai chaacteistics f the shavig cutte, such as pfile, helix ad pitch, is mally pefmed CNC ispecti uits (Kligeleg, Hefle, M&M, etc.) which guaatee a extemely high measuemet accuacy. The epeataility f the vaius measuemets is i the aea f a few mics. Pfile ad helix ispectis d t pse ay paticula plem, except f the fact that whe yu check the pfile yu have t psiti the pe all suely i the middle f a seati tth. As fa as the helix is cceed, yu will tai a gaph that put it evidece the iteupti due t the seatis spaces, ut the eadig f the shape des t peset ay difficulty. It is ecessay t g me i detail f the pitch ad ecceticity es. The plems cme whe yu have t ispect shavig cuttes with helical seatis ( ffset ), i.e. the cuttes wkig udepass ad pluge. Oce yu psiti the pe, whe yu tate the cutte t e ale t check the ext teeth, it is als ecessay t mve the pve lgitudially f the same amut f the ffset f each tth, thewise, afte e tw teeth the pe wuld fall it the empty space. Fig.N 5- F the pitch ispecti f udepass a pluge cuttes a special sftwae is ecessay

5 If it is a cutte with theetical ivlute, the pcedue wuld e ve, ut if, as it feuetly happes, the helix is hllw, the lgitudial mvemet f the pe wuld cause the pe t tuch the flak i diffeet aeas, i.e. i pits whee the tth has a diffeet thickess. The ispecti euipmet wuld detect this as a pitch e. The checkig euipmets f shavig cutte ispecti ae mally edwed with a apppiate sftwae that t ly mves the pe accdig t the seatis ffset, ut als takes it accut the measuemet vaiatis due t the helix hllw. A mal checkig euipmet that is t edwed with such special sftwae cat check the pitch udepass ad pluge shavig cuttes. The pitch ispecti is pefmed y tuchig evey tth th flaks. I pactice the euipmet detemies the psiti i the space f all the teeth flaks. These data ae elaated ad a apppiate sftwae detemies which is the ecceticity f the tthig F, as if this last paamete is measued y tuchig each space with a sphee a lle.