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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The tolerances and allowances etated’in the following Tables apply to gears according to D M Sheet 1, Section 2. The t o t a l composite error according t o Section 4.
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.
If the c h a r t feed i s operated and a t ra c e drawn corresponding t o t he upper and lower allowance, two concentric c i r c l e s a r e obtained if the recording i a made in pol ar Co-ordinates see Figure 5 and two p a r a l l e l s t r a i g h t lines i f the recording i s made i n rectangular Co-ordinates see Figure 6.
Por h e l i c a l spur gears cosao i s dun by cosaos and cosab by cosab. 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?
For gears with V t e e t h fin h e following apply: For denomination of contact f aces and of the relevant qual i t y i ndi cessee Figure 1 and 2 ; f o r marking the d i f f e r e n t ear blank shapes, see reference regarding Sup, plementary Sheet 2 i n DIN Sheet I page Measuring plane parallel witEa centre distance line Figure 8 E r r o r in axial parallelism f p s.
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 tanuent lenRth allowancea; dual cone width allowances; Dem.
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 588405 Gear f i t s not l i s t e d i n this Table should be specified only i n exceptional circumstances.
I ma -4 -ea -n -w – above 6 to I2 hove 0. In this case the permissible radial eccentricity for the tip circle should be taken from Table 3. 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: The reference axis f o r the radial eccentricity is the axis of the mounting bore see Figure 1 or the axis of the gear seating diameter see Figure 2 or the axis of the two centre holes see Figure 3.
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.
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.
This i s why permissible v a ri a t i o n s a r e specified for the gear blank i n accordance w i t h the required qua l i t y of the tooth system.
Base tanuent lenuth allowances; dual cone width allowances; Dem. Minor var iat i o n s may, however, a r i s e in this connection because the individual allowances have been rounded t o preferred numbers.
For grades P 8 it is recommended that the tip cylinder should be used for setting up the gear blank, or that test flanges should be provided. The ideal involute surface corresponding to the nominal dimension and shown in Figure 4 is outside the boundary involutes because of the negative base tangent length allowances see a l s o DIN Sheet IFigure I. 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.
This i s performed a s follows: 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. 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.
I test flanges a r e provi0ed f o r setting up purposes, the permissible radial eccentricity f applies t o these. Assuming t h a t t h e gear t o be t e s t e d i s within the scope according t o D I N Sheet 1, Sect i o n 2, the centre distance of s t r a i g h t or h e l i c a l spur gears without addendum modification i s set on the dual flank r o l l t e s t e r a s folows: Permissible radial eccentricits for tip cylinder when this is n o t used for settinn UE Table 4 Permissible radial eccentricity f o r.
The acceptance for tooth Systeme mainly consists of a cumulative e r r o r testing r o l l testing. In this case the permissible axial eccentricity TAa is: The difference between the upper and the lower allowance of the tip circle ia appended as a minus tolerance.
If the shaft and gear are made in one dln, the radial eccentricity between the mounting In the milling machine 0. In t h i s connection i t should be noted i n p dib r t i c u l dkn 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 t h e i r geometrical and position var i at i ons determine t he qual i t y of th e tooth system.
For any given bearing a l l the s t at i onar y par t e belong t o the housing and a l l the p a r t s r o t a t i n g with the gear belong t o the shaft f o r permissible variat i o n of dim “shaft” see Table I columu I O.