授課課題鍵、花鍵的互換性（Teaching topics interchangeability of keys and splines）

1、授課課題鍵、花鍵的互換性（Teaching topics interchangeability of keys and splines）Documents from the network, I collected, finishing, and if there are omissions, errors, but also please correct me!The eighth chapter is the tolerance and coordination of keys and splinesTeaching topics: tolerances and fits of keys

2、and splinesObjective requirements: 1. Understand the types and characteristics of flat and rectangular spline combinations;2. Master the features of the tolerance and fit of the flat and rectangular spline connections; master the centering mode of the rectangular spline connections;3. Understand the

3、 features of tolerances and fits of involute splines;4. Understand the marking of flat keys and rectangular splinesKey points: 1. The selection and marking of tolerances and fits of flat keys;2. Selection and marking of tolerances and fits of rectangular spline connectionsDifficulties: selection of

4、tolerances and fits for rectangular spline connectionsThe key role of bond and spline in a machine:Used to connect gears and pulleys on shafts and shafts to deliver torque;A relative axial movement between the shaft and the transmission requirements, the key can play a guiding roleTypes of keys: mai

5、nly divided into single button and splineSingle key is divided into flat key, semicircle key and wedge key and so onAmong them, flat key is the most widely usedThe horizontal key can be divided into plain flat key and guiding flat keyPlain flat keys are generally used for fixed connections, whereas

6、plain keys are used for movable connectionsThe shape of spline key is different from rectangular spline, involute spline and triangle spline, among which rectangle spline is applied mostThis section deals with the design of the combination of flat and rectangular splinesFigure 8-1 key connection dia

7、gram 8-2 single keyAccuracy design of flat key jointInclude: 1. dimensional accuracy design2. shape accuracy design3. accuracy design of surface roughness1. dimensional accuracy designThe basic structure of flat key joint:The flat key joint is composed of a key, a shaft keyway and a hub keywayAt wor

8、k, the torque is transmitted through the side of the key to contact the shaft groove and the side of the hub grooveMating dimensions of flat keys: B(non mating size: L (key length) and H (key height)T (shaft groove depth) and T1 (hub groove depth)D (shaft and hub groove diameter)Figure 8-3 flat key

9、connectionUse requirements:Side force transmission requires adequate effective contact areaThere is a certain clearance between the upper surface of the key and the hub slot (0.2-0.5)The key is firmly embedded; the utility model is convenient for assembly and disassemblyFactors affecting the use of

10、flat key connections and control:1) factors affecting the use of flat key connectionsFit the surface shape error of the surface: the symmetry error of the surface to the axis of the hole and axisMatching surface roughness: the roughness of the contact surface between the key and the keyway2) control

11、 of the factors that affect its useKeys are standard parts, so the control of influencing factors is mainly to the keywayGive a strict tolerance to the mating size and give a looser tolerance to the non mating sizeThe degree of symmetry between the central plane of the width of the axis keyway, the

12、central plane of the axis and the width of the hub groove, and the symmetry of the reference axis of the boreThe matching surface of the keyway gives a strict allowable value of the surface roughness, rather than the matching surface, giving a looser surface roughness valueDetermination of tolerance

13、s and fits of flat key connections:1) tolerances and combinations of key and keyway dimensionsMatching system: base shaft systemThe accuracy of the flat key connection has been normalized: the key width defines a tolerance zone: H9; the shaft groove and the hub groove define three tolerance zonesFor

14、med three kinds of coordination: loose, general, tight connectionLoosely connected; generally tightFig. 8-4 diagram of tolerance and coordination of flat keysTable 8-1 tolerances and fits of the width of the flat key, the width of the groove and the width of the groove of the hub2) tolerances for fl

15、at and keyway non mating dimensionsKey to:h11Horizontal key length L:h14Axial groove length L1:H14Limit deviation of shaft groove depth T and hub groove depth by T1 (see table 10.3 to determine the standard textbook for measurement, respectively), mark (D-T) and (d+t1), according to the deviation de

16、viation corresponding T and T1 selection, but the deviation (D-T) should take a number (-)2. shape and tolerance of keywayIn order to ensure that the sides of the key and the keyway have sufficient contact area and avoid assembly difficulties, the national standard specifies the tolerances for the k

17、ey and keyway in form and position:(1) because the actual center plane of the keyway is skewed in the radial direction and axial direction, the symmetry error of the keyway is caused, and the symmetry tolerance of the shaft groove and the hub groove to the axis should be specified respectivelyThe to

18、lerance grade of symmetry is selected according to the national standard GB/T 1184-1996, and the general grade is 79(2) when the ratio of the length of flat keys to L and the width of B is greater than or equal to 8, the parallel requirement of the length of the two working side of the key width B s

19、hould be specifiedWhen B = 6mm, 7 tolerance grade level; when B is larger than 836mm, the tolerance level 6 level; when B is larger than 40mm, the tolerance level 5 level3. surface roughness of keywayThe maximum value of the Ra with the matching surface is 1.6-3.2; the maximum value of the Ra of the

20、 non matching surface is 6.3According to GB/T1184-1996 shape and location tolerances, non injection tolerance value, selected level 7-94. Examples of axis dimensioning:Mark groove depth, D-T and toleranceLabeling slot width, B and toleranceMarking symmetry toleranceMark surface roughnessFigure 8-5 a

21、xis callout5, wheel marking examples:Mark wheel depth, d+t1 and toleranceLabeling slot width, B and toleranceMarking symmetry toleranceMark surface roughnessFig. 8-6 marking of wheel hubTwo. Tolerances and fits of rectangular splinesCompared with the key connection, it has high centering precision,

22、good guidance and strong bearing capacity, so it has been widely used in mechanical productionThere are many kinds of spline connections, but the most widely used ones are rectangular splines1. Requirements of rectangular spline, geometric parameters and centering method1) geometrical parameters of

23、rectangular splineMain dimensions: small diameter D, big diameter D, key and keyway B;The number of keys N is even numbered: 6, 8, 10, three2) use requirements:Figure 8-7 rectangular splineA) centering requirements for internal and external splines(b) side transmission requires a sufficiently large

24、and effective contact areaC) for sliding splines, the internal and external splines need a clearanceD) accurate requirements for indexing of splines3) centering: path centeringThe rectangular spline is composed of multiple surfaces, the main structural dimensions are large diameter (D), path (d) and

25、 key width (B), and these parameters also have the mating size and the non mating sizeFrom a standardized point of view, no matter what type of size, the tolerance can also be used tolerance and coordination national standardsIn a rectangular spline combination, it is difficult to couple the interna

26、l and external splines with large diameter D, path D, and key width B at the same time that the corresponding joint surfaces are well coupledBecause these 3 dimensions are a manufacturing error, and even if these 3 dimensions are very accurate, but also between the corresponding surface position err

27、or, in order to ensure the use of performance, improve the processing technology, choose only one combination as the main mating surface of the required high precision, to ensure the coordination properties the surface and centering precision, called centering surfaceBecause the hardness of the spli

28、ne joint surface is usually higher, heat treatment is often needed during the processIn order to ensure the dimensional accuracy and shape accuracy of the centering surface, grinding is required after heat treatmentFrom the point of view of processing technology, the path is easy to grind, easy to g

29、uarantee higher machining accuracy and surface hardness, and can improve the wear resistance and service life of the splineTherefore, the standard for rectangular splines requires small-diameter centeringThe large diameter of the spline hole and keyway to side grinding, the non centering size can be

30、 specified tolerance level is low, but because of the key side of torque transmission, so the key side size tolerances required a higher level2. The design of the accuracy of the rectangular spline1) dimensional accuracy design:Internal and external spline size tolerance tape: see textbook 11-7Match

31、ing system: base hole systemSelection of matching types: mainly depends on the relative motion requirements of the internal and external splines: table 11-7(a) relative motion requires frequent application of slip fit;(b) without relative movement requirements, the use of fixed fit;C) the centering

32、accuracy is high, and the fixed fit is adopted; the low requirement can be used for sliding fitLarge diameter non centering diameter, the combination of internal and external spline D surface should have a large gap, so the standard stipulated by H10 / a11 with either general purpose or precision tr

33、ansmission of the spline, only this kind of cooperation2) determination of internal and external spline position tolerancesA) the limit dimension of the path D follows the inclusion principle: the path is the centering fit dimension, ensuring the mating performance, and the surface tolerances of its

34、 shapeAnd dimensional tolerances comply with the inclusion principleB) the position tolerance of the spline follows the maximum solid principle (batch)The position tolerance of the spline controls the angular position between the keys of each spline, the symmetry error of each key to the axis, and t

35、he parallelism error of each key to the axisIt complies with the principle of maximum substance(position tolerance is shown in table 10.7 of the textbook)C) the symmetrical tolerances and equal degrees tolerances of keys and keyway are observed in accordance with the independent principle (single or small batch)Sym