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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I n t h e equations gear 2 is t h e master gear. The c e n tre distance a” i s then reduced each time by the upper and louer allowance of the 5805 tangent length converted t o the r a d i a l direction.
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?
Page 4 DIN Sheet 2 2. The following 2 measuring planes a re distinguished: The values specified relate to the bearing when inetalled.
The reference diameter to which the axial eccentricity is related is found as: In this case the permissible axial eccentricity TAa is: Base tannent lenRth allowances; dual cone width allowances; Derm. This i s performed a s follows: Por h e l i c a l spur gears cosao i s replaced by cosaos and cosab by cosab.
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. 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.
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. 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.
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 centre distance a” can be s e t by placing the appropriate s l i p gauges between t he two mounting a rb o rs or the individual arbors. 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.
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 test flanges a r e provi0ed f o r setting up purposes, the permissible radial eccentricity f applies t o these. 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. 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 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.
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 eccentricity Tea is specified in Table 5. 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 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. 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 e r r o r i n a x i a l parallelism i e designated by Spa.
dln Measuring plane perpendicular with centre distance line 6 Tolerances f o r uear assemblies. If the shaft and gear are made in one piece, the radial eccentricity between the mounting In the milling machine 0.
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.
Base tanuent lenRth allowancea; dual cone width allowances; Dem. I f one of these requirements i s over-stepped the new conditions which r e s u l t regarding clearances, accuracy of sin, tooth engagement conditions, etc. 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. DIN tol f cylindr 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: Measuring plane parallel witEa centre distance line Figure 8 E r r o r 5840 axial parallelism f p s.
The face alignment error is designated as pos i t i ve 558405 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 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 acceptance for tooth Systeme mainly consists of a cumulative e r r o r testing r o l l testing. For grades P 8 it is recommended that fin tip cylinder should be used for setting up the gear blank, or that test flanges should be provided.
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 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 ein the teet result.
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 dinn 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.
Che allowances a r e the same a s the base tangent length allowances divided by the sine of the pressure angle. 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 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 diin c te.
The c e n t re distance allowances apply t o housings with gears according t o Dl3 Sheet 1, Section 2. 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. 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 s t of a l l the points which must be taken i n t o account when choosing a gear f i t. The t o t a l composite error according t o Section 4.
Base tanuent lenuth allowances; dual cone width allowances; Dem.