Design and calculation of the hottest V-belt drive

2022-07-24
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Design calculation of V-belt transmission

1 failure forms and design criteria of V-belt transmission

according to the analysis of the working conditions of belt transmission, the main failure forms of V-belt transmission are:

⑴ fatigue fracture of V-belt: the stress on any cross section of the belt will change circularly with the operation of the belt. When the stress cycle reaches a certain number of times, that is, after running for a certain period of time, V-belt has fatigue crack delamination locally, and then loose state or even fracture occurs, resulting in fatigue damage and loss of transmission capacity

⑵ slipping: when the external working load exceeds the maximum effective tension of V-belt transmission, the belt and small pulley slide relatively along the whole working surface, resulting in transmission slipping failure

therefore, it is the design and calculation criterion for the working capacity of V-belt transmission to ensure that the belt has certain fatigue strength and life without slipping

the rated power that a single V-belt can transmit without slipping and with a certain fatigue life P is

2 V-belt transmission design steps and transmission parameter selection

1. select the V-belt model

v-belt with many types, such as ordinary V-belt, narrow V-belt, wide V-belt, large wedge angle V-belt, etc., of which the common V-belt is the most widely used, and the use of narrow V-belt is also increasingly widespread

ordinary V-belt is composed of top glue, tensile body (bearing layer), bottom glue and wrapping cloth, as shown in Figure 11.9. The tensile body is composed of cord fabric or cord group, such as WDW (5) 0 external wall insulation material testing equipment, on-site puller, YH (4) 0b constant temperature and humidity curing box, JJ (5) mixer, etc. it is the main body bearing the load tension. The upper and lower top glue and bottom glue respectively bear the tensile and compressive deformation during bending. The common V-belt with rope structure has the characteristics of good flexibility and is suitable for occasions with small pulley diameter and high speed

figure 11.9

the narrow V-belt uses synthetic fiber rope or steel wire rope as the bearing layer. Compared with the ordinary V-belt, when the height is the same, its width is about 30% smaller than the ordinary V-belt. The power transmission capacity of narrow V-belt is greater than that of ordinary V-belt, with high allowable speed and deflection times, and small transmission center distance. It is suitable for transmission with high power and compact structure

ordinary V has seven models y, Z, a, B, C, D and E, and narrow V has SPZ, spa, SPB and S. for example, data PC, they will announce four models of product prices at the same time. See table 11.1 and table 11.2 for the cross-sectional dimensions and pulley groove dimensions of various types of belts

v belts are made into rings without joints. See Fig. 11.10 for the reference length of various types of belts

figure 11.10 reference length of V-belt ld

the model of V-belt can be selected according to the calculated power PC and small pulley speed n1. See Figure 11.11 for ordinary V-belt and figure 11.12 for narrow V-belt. Calculated power

pc=kap (11.12)

where Ka is the coefficient of working conditions, see table 11.3

p-- nominal transmission power (kw)

when the working condition is located in the adjacent area of two models, the two models can be selected for calculation, and finally the better one can be selected for analysis and comparison

2. Determine the pulley reference diameter

on the v-pulley, the pulley diameter corresponding to the pitch width BP of the V-belt used is called the reference diameter DD. see table 11.4 for the pulley reference diameter series

the smaller the pulley is, the more compact the transmission size structure is. However, the greater the bending stress of the belt is, the belt is easy to fatigue fracture. In order to avoid excessive bending stress, the minimum pulley reference diameter ddmin is specified for various types of V-belts, as shown in table 11.5

figure 11.13

⑶ actual center distance

7 Determining the initial tension of the belt

is an important factor to ensure the normal operation of the belt drive. The initial tension is too small, the friction is small, and it is easy to slip; The initial tension is too large, and the service life of the belt is low. It can be used for food planting and commercial greenhouses, and the bearing capacity of the shaft is large. It is recommended that the initial tension F0 of a single V-belt after tensioning is

figure 11.14

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