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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DIN tol f cylindr Gear f i t s not l i s t e d i n this Table should be specified only i n exceptional circumstances. Recommendation f o r t h i s purpose i a given in column 4 t o 20 i n Table 1.
They a r e intended t o serve t h e designer as a check l i dkn t of a l l the points which must be taken i n t o sin when choosing a gear f i t.
I n t h e case of housings made of aluminium a l l o y s and s i m i l a r materials, s u i t a b l e measues should be taken, e. I f one of these requirements i s over-stepped the new conditions which r e s u l t regarding clearances, accuracy of transmission, tooth engagement conditions, etc.
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 If the shaft and gear are made in one piece, the radial eccentricity between the mounting In the milling machine 0.
The values specified relate to the bearing when inetalled. 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.
Page 4 DIN Sheet 2 2. Gear blank f dim r gear with external t eet h Bearing seating diameter Centre hole Figure The q u a 58045 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 dni 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.
In t h i s connection i t should be noted i n p a r t i c u l a 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 dinn 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 denomination of djn 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 G e a r b l a n k s f o r t o p p e d s p u djn s e a r a Since i n t h i s case the t i p cylinder is djn 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.
I the tip circle tip cylinder is 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. I test flanges a r e provi0ed f o r setting up purposes, the permissible radial eccentricity f applies t o these. In this case the permissible radial eccentricity for the tip circle should be taken from Table 3. 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 reference axis f o r the radial eccentricity is the axis of the mounting bore see Figure 5805 or the axis of the gear seating diameter see Figure 2 or the axis of the two centre holes see Figure 3. Permissible radial eccentricits for tip cylinder when this is n o t used for settinn UE Table 4 Permissible radial eccentricity f o r. For the end faces of a gear blank which are used as contact face o r clamping face the permissible axial dun Tea is specified in Table 5.
The reference diameter to which the axial eccentricity is related is found as: In this case the permissible axial eccentricity TAa is: 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 58045 contact face, a permissible degree of non-parallelism should 85405 specified see Figure?
The difference between the upper and the lower allowance of the tip circle ia appended as a minus tolerance. This dimension must not be entered in the drawing redundant dimensioning; see DIN Sheet 3.
Dij acceptance for tooth Systeme mainly consists of a cumulative e r r o r testing r o l l testing. 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.
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. The following are distinguished: Since the 5840 flank roll testing is generally carried out as a final inspection, and since it cannot be performed until the teeth have been finished, base tangent length and dual cone width allowances have been specified during manufacture measurement of tooth thickness.
These allowances, together with the centre distance allowances, are the criteria for a gear fit. 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. Base tangent length allowances and t h diin 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 dinn This i s performed a s follows: 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 djn 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: I n t h e equations gear 2 is t h e master gear.
Por h e l i c dun l spur gears dun i s replaced by cosaos and cosab by cosab. The centre distance a” can be s e t by placing dib appropriate s l i p gauges between t he two mounting a rb rin rs or the individual 58045. The c e n tre distance a” i s then reduced each time by the upper and louer allowance of the base tangent length converted t o the r a d i a l direction.
For s t r a i g h t or h e l i c a l spur gears without addendum don 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: For gears with V t e e t h t h e following apply: 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 558405 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 5840 i g h t lines i f the recording i dib made i n rectangular Co-ordinates see Figure 6.
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.
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 t o t a l composite error according t o Section 4. Che allowances a r e the same a s the base tangent length allowances divided by the sine of the pressure angle.
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.
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.
Aw irI 2 lana, 50 lover allovanc. I f the upper and lower allowances of the dual f lank r o l l t e s t distance have been recorded according t o Section 4.
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. 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.
DIN – European Standards
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.
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 the “shaft” see Table I columu I O.
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.
The c e n t re distance allowances apply t o housings with gears according t o Dl3 Sheet 1, Section 2. They should be taken from the Tables i n Section 6 t o s u i t the gear f i t selected grade and tolerance zone. The following 2 measuring planes a re distinguished: The e r r o r i n a x i a l parallelism i e designated by Spa. Measuring plane parallel witEa centre distance line Figure 8 E r r o r in axial parallelism f p s.
Measuring plane perpendicular with centre distance line 6 Tolerances f o r uear assemblies. The tolerances and allowances etated’in the following Tables apply to gears according to D M Sheet 1, Section 2.
For gears not covered i n the scope it may be necessary i certain circumstances to modify the n allowances and tolerances. Base tanuent lenRth allowancea; dual cone width allowances; Dem. I ma -4 -ea -n -w – above 6 to I2 hove 0.
Base tannent lennth allowances; dual cone width allowances; perm. Base tanuent lenuth allowances; dual cone width allowances; Dem.
Base tannent lenRth allowances; dual cone width allowances; Derm.