Por d i f f e r e n t f i e l d s of application involving f i n e mechanics, see D I N Sheet 1 Section 4, Table I column 1 s p e c i f i e s a range. DIN Spur Gear Drives for Fine Mechanics; Tables. DIN Spur Gear Drives for Fine Mechanics; Indication in Drawings, Examples for Calculation.
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This i s performed a s follows: For gears with V t e e t h t h e following apply: Page 4 DIN Sheet 2 2. The ideal involute surface corresponding to the nominal dn and shown in Figure 4 is outside dun boundary involutes because of the negative base tangent length allowances see a l s o DIN Sheet IFigure I. For s t r a i g h t or h e l i c a l spur gears without addendum modification assuming that the gear t othe r e s u l t i n g dual be t e s t e d i a within t h e scope according t o DIB Sheet I Section 2 f l a n k r o l l t e s t distance allowances a r e as follows: Measuring plane perpendicular with centre distance line 6 Tolerances f o r uear assemblies.
In this case the permissible radial eccentricity for the tip circle should be taken from Table 3. I the tip circle tip cylinder dun used for setting up the gear blank on the gear-cutting f machine, the radial eccentricity of the gear blauk according to Table 4 should be observed.
The cumulative error can be found by rolling the gear to be tested with a master gear, f o r which purpose the total composite error of the master gear must be known and, where necessary, deducted from the teet result. This dimension must not be entered in the drawing redundant dimensioning; see DIN Sheet 584005.
The c e n t re distance allowances apply t o housings with gears according t o Dl3 Sheet 1, Section 2. In this case the permissible axial eccentricity TAa is: The tolerances and allowances etated’in the following Tables apply to gears according to D M Sheet 1, Section 2.
They a r e intended t o serve t h e designer as a check l i s t of a l l the points which must be taken i n t o account when choosing a gear f i t. In the came of instrument drives it is recommended, particularly when mounted overhung, that ball bearings with increased radial clearance ehould be used and proloading applied. Gear f i t s not l i s t e d i n this Table should be specified only i n exceptional circumstances.
The values specified relate to the bearing when inetalled. Por h e l i c a l spur gears cosao i s replaced by cosaos and cosab by cosab. For the end faces of a gear blank which are used as contact face o r clamping face the permissible axial eccentricity Tea is specified in Table 5. The following are distinguished: The uncertainty i n measurement due t o var i at i on of the measuring Observance of t h e s p e c i fi e d allowances may be determined d i r e c te.
Gear blank f o r gear with external t eet h Bearing seating diameter Centre hole Figure The q u a l i t y of a tooth system depends very l ar gel y on the accuracy of the gear blanks. The e r r o r i n a x i a l parallelism i e designated by Spa. When gears f o r which the gear blanks are disc-shaped are to be cut in batches, then, instead of a pemissible axial eccentricity for the face farthest from the contact face, a permissible degree of non-parallelism should be specified see Figure?
The cumulative error of a tooth system is the common and simultaneous effect of a number of individual errors on the ideal position and geometry of the tooth flanks.
DIN – European Standards
The c e n tre distance a” i s then reduced each time sin the upper and louer allowance of the base tangent length converted t o the r a d i a l sin. Base tannent lenRth allowances; dual cone width allowances; Derm. Che allowances a r e the same a s the base tangent length allowances divided by the sine of the pressure angle.
If the shaft and gear are made in one piece, the radial eccentricity between the mounting In the milling machine 0.
Recommendation f o r t h i s purpose i a given in column 4 t o 20 i n Table 1.
Like the base tangent length allowances, compliance with the dual cone width allowances can a l s o be determined by t h e dual flank r o l l t e s t i n The procedure i s the same as t h a t described under Section 4.
In t h i s connection i t should be noted i n p a r t i c u l diin r t h a ti n the case of disc-shaped gear blanks i n which t h e length of bore i a not s u f f i c i e n t t o support the gear blank during the gear-cutting procese, the end faces serve ae contact faces during the gear-cutting process and hence cin h e i r geometrical and position var i at i ons determine t he qual i t y cin th e tooth system. The face alignment error is designated as pos i t i ve if t he var i at i on i s i n the right-hand dir e c t i o nand negative i f i t i a i n the left-hand di r ect i on with reference t o the design value n of the h e l i x angle Bo.
The s l i p gauges a re then removed, t h e two gears ar e mounted on the arbors, brought i n t o cont a c t and r o l l e d one on the other. Base tannent lennth allowances; dual cone width allowances; perm. The acceptance for tooth Systeme mainly consists of a cumulative e r r o r testing r o l l testing. Base tanuent lenRth allowancea; dual cone width allowances; Dem.
G e a r b l a n k s f o r t o p p e d s p u r s e a r a Since i n t h i s case the t i p cylinder is machined by the gear-cutting t o o lthe t i p cylinder of the gear blank i s given a machining allowance which may differ according t o t h e gear-cutting method used. Minor var iat i o n s may, however, a r don s e in this connection because the individual allowances have been rounded t o preferred numbers.
In connection v i t h the s e l e c t i o n of b a l l b e d n g e i t should be noted t h a t the tolerance allowed f o r t he bearing bores Q i n t h e housing r e l a t i v e t o the tolerance on t he centre distance Ta must be reduced by the amount of the r a d i a l run-out of the b a l l bearing outer ringe frL.
I n t h e equations gear 2 is t h e master gear.
Tolerances and allowances for housing AB understood in this Standard, t h e t e m housing r e f e r e t o the component connecting the bearings of a p a i r of mating gears. The t o t a l composite error according t o Section 4. If p l a i n b e a r i n g s are uaed, t h e i r dimensional and geometrical accuracy should be i n line with t h e correaponding i i w s for b a l l boaringo according t o D I N Base tangent length allowances and t h e i r boundary involutes The base tangent length allowances a r e r e l a t e d t o the tooth thickness allowances as follows: The e r r o r t r a c e must remain between the two l i n e s previously drawn which represent the bounda r i e s of t h e tolerance zone.
The reference diameter to which the axial eccentricity is related is found as: FP With c i r c u l a r e r r o r t r a c e s see Figure 5 the upper dlovance of dual flank roll teat distance – – Figure 5. I test flanges a r e provi0ed f o r setting up purposes, the permissible radial eccentricity f applies t o these.
Measuring plane parallel witEa centre distance line Figure 8 E r r o r in axial parallelism f p s. DIN tol f cylindr Permissible radial eccentricits for tip cylinder when this is n o t used for settinn UE Table 4 Permissible radial eccentricity f o r.
I ma -4 -ea -n -w – above 6 to I2 hove 0.