Jun 27, 2017

Edge drive Tube Mills is building materials, metallurgy and mining industries common grinding equipment, the transmission parts of the size of the gear directly affect the normal use of the mill. Analysis of the causes of vibration from many aspects, to avoid misunderstanding, for the design, manufacture, installation and use of reference.

1 design reasons

1.1 gear force direction

The Tube Mills is designed to take into account the direction of the gears of the gears in the gear drive, and the equipment base does not bear the component force in the horizontal direction. As shown in Fig. 1, the relationship between the size gear position sizes E and a and the pressure angle αn isCos αn = E / a.

For the standard cylindrical spur gear or non-variable cylindrical helical gear drive, based on the relationship between the size of the relationship between the size of the gear position, the size of the gears in the horizontal direction is not subject to thrust, and therefore not because of the horizontal component is too large vibration.

Pipe mill is usually used to change gears. Germany's Bohmann as early as 1976 on the big gear, and that should be prohibited in the Tube Mills on the use of fixed gear. The meshing angle α '> αn of the displacement gear. According to the calculation formula, if the modulus mn = 30, the pressure angle αn = 20 °, the total number of teeth z Σ = (32 + 216), the total displacement coefficient x Σ = 2.8 gear engagement angle α '= 23.03 °, More than αn 3.03 °, the horizontal component of about 5% increase.

Therefore, the large displacement gear according to the pressure angle αn to determine the size of the gear mounting position, will inevitably cause its force f away from the vertical upward direction, so that the foundation to bear the horizontal force, resulting in the foundation and equipment vibration hidden. In the design should take full account of the angle of engagement on the direction of the force of the gear; therefore, large gears gear position size should be used the following relationship is most reasonable, that is,

The range of helix angle β takes into account the coincidence degree and the smoothness of the transmission. Small modulus multi-tooth gear in operation, due to the polygon effect is not obvious, so the operation is smooth, instantaneous transmission ratio is also a larger modulus of the gear to be accurate, with small noise, small vibration and small dynamic load advantages. To this end, in the design of gear transmission, the structural strength of the allowable conditions, should try to choose a small modulus gear.

It can be seen from Table 1 that the total coincidence degree of small helix angle gears with β is 2 ° ~ 5 ° is 17.4% ~ 48.3% higher than that of spur gears. From Table 2, it can be seen that the same modulus, different gears Coincidence degree, multi-tooth ratio is less than the number of teeth; can be seen from Table 3, small modulus multi-tooth gear pair of coincidence than the large modulus of the number of teeth high. It can be explained that the modulus, the number of teeth and the slope are related to the gear vibration.

The main reason for gear wear is that the tooth surface is relatively sliding, and the maximum sliding rate of the two gears is equal or similar as the optimization target of the gear displacement coefficient. Properly assigning the displacement coefficient of the two gears so that their maximum sliding rate is comparable or close, which can reduce the contact stress of the tooth surface and improve the anti-gluing and wear resistance of the gear. When the total displacement coefficient Reasonable distribution, sliding rate difference is very small, more conducive to extend the gear life.

Pipe mill gear diameter is generally more than 3.5 m, the national standard gear accuracy of 9-8-8 level, it is difficult to achieve higher processing accuracy. The larger the tooth width coefficient, the more uneven the load along the tooth width distribution, the tube gear tooth width coefficient is generally not more than 0.8 is appropriate.

(1) large ring gear wheel flange stiffness on the vibration of a greater impact, and even cause the wheel rim fracture;

(2) the deformation of the Hafi surface caused by large pitch error, resulting in impact, due to the buffer function is not obvious, resulting in Hough surface outside the studs produce tensile plastic deformation and fracture, resulting in vibration;

(3) Hough facies joint double-headed stud at the back groove to produce vibration;

(4) the size of the number of teeth are not intertwined teeth uneven wear, causing vibration;

(5) for the larger diameter of the Tube Mills cylinder, the shaft deflection of the larger vibration.