DIN 3961-1978圆柱齿轮啮合公差基础

DIN 3961-1978圆柱齿轮啮合公差;基础

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DIN 3961-1978圆柱齿轮啮合公差;基础

Page 2 DIN 3961

1.2 Gear tooth tolerances, system of gear fits To make sure a t all times that, apart from the interchangeability of the gears of gear transmission units which is governed by the mating dimensions, the respective functional requirements such as quiet running, trueangle transmission, lubrication facilities, loading capability, are upheld, it is essential for the deviations of certain parameters of the gear teeth as well as the mounting dimensions in the gear housing to be held within certain limits. The system of gear fits resembles the system for cylindrical fits. For each of the gears of a gear pair all form deviations, pitch deviations etc. lie within the dimensions of two notional, error-free, concentric gears, the tooth centres of which do not need t o coincide with those of the working gears, and the tooth thicknesses of which differ from the nominal dimension by the amount of the upper allowance in the case of one of the gears, and by the amount of the lower allowance in the case of the other gear. The backlash results not only from appropriately chosen allowances of tooth thickness, but also from the allowance of the centre distance and other individual deviations. The magnitude and scaling of the tooth thickness allowances are thus in a given ratio t o the magnitude and scaling of the centre distance allowances. Just as with I S 0 cylindrical fits there are two systems of fits, the hole basis and the shaft basis, so also are there two systems of gear fits, namely the centre distance basis and the tooth thickness basis. With the former, only one tolerance zone of the centre distance i s used and the magnitude of the clearance i s established by different tolerance zones of the tooth thickness. With the tooth thickness basis system the opposite applies. The sizes of the gear tooth tolerances are developed on the same principles as the tolerances for cylindrical fits. Thus, just as the latter are designed for accuracies which exceeded the requirements existing a t thc time of their origin, and are still in advance of their time, so also are the gear tooth tolerances arranged such that in all probability more exacting requirements and improved measuring methods available in the future are catered for.DIN 3962 Part 1 to Part 3 contain the tolerances for deviations of individual parameters of cylindrical gear teeth. DIN 3963 contains the tolerances for working deviations. DIN 3964 contains the centre distance allowances and shaft position tolerances for housings for cylindrical gear transm issio ns. DIN 3967 contains the system of gear f i t s with data on backlash, tooth thickness allowances and too

th thickness tolerances. The basis specified for the system of gear f i t s i s that of the centre distance. For this purpose it IS necessary so to arrange the centre distance allowances that when using gear transmissions with external and internal teeth the centre distance allowances are indicated in the same way, and in gear transmissions with many pairs of gears no unacceptably large deviations from the nominal dimension arise in the distance from the first t o the last transmission shaft. The limiting allowances are thus disposed symmetrically relative t o the zero line. The kind of gear tooth fit i s determined through the choice of

the upper allowance and the tolerance on tooth thickness in DIN 3967 and through the choice of zone for the centre distance allowances in DIN 3964.

1.3 Scope DIN 3962 Part 1 to Part 3 and DIN 3963 contain tolerances for gear teeth on cylindrical gears of module 1 t o 70 mm and with reference circle diameters d up t o 10 O00 mm, graded in 12 gear tooth qualities. The tolerances apply regardless of the pressure angle. For checking tooth thickness and determining backlash, the working pressure angles and helix angles have to be taken into account, see DIN 3967. For d exceeding 10 O 0 0 mm tolerances can be agreed which can be calculated by using the formulae given in Section 3.5.1 and in Section 3.5.2. I n the case of racks, the tolerances for their teeth shall not exceed those for the teeth of the mating gear. If the manufacturer has no knowledge of the mating gear, he may make the rack length equal to the mating gear circumference.

2 Other relevant StandardsDIN 3960 Definitions and parameters for cylindrical gears and cylindrical gear pairs with involute teeth DIN 3962 Part 1 Tolerances for cylindrical gear teeth; tolerances for deviations of individual parameters DIN 3962 Part 2 Tolerances for cylindrical gear teeth; tolerances for tooth trace deviations DIN 3962 Part 3 Tolerances for cylindrical gear teeth; tolerances for pitch-spandeviations DIN 3963 Tolerances for cylindrical gear teeth; tolerances for working deviations DIN 3964 Centre distance allowances and shaft position tolerances of housings for cylindrical gear transmissions DIN 3967 System of gear fits, backlash, tooth thickness allowances and tooth thickness tolerances; bases, calculation of tooth thickness allowances, conversion of allowances for the different measuring methods

3 Structure of the tolerance system3.1 Tolerance relationships The DIN gear tooth tolerance system has been derived from long experience in gear production. The aim has been as far as possible so to coordinate the various tolerances with one another that in a given gear tooth quality they correspond approximately to the average relationships in which the deviations occur in production. The bases of the tolerance system are thus productionoriented; the way in which this system can also be used for tolerancing to suit different functional requirements i s described in Sect

ion 4. The numerical equations for the tolerances and the values calculated from them in DIN 3962,Part 1, DIN 3963, DIN 3964 and DIN 3967 have …… 此处隐藏：6125字，全部文档内容请下载后查看。喜欢就下载吧 ……