The noise sources are common mechanical equipment?

On the issue of the mechanical equipment noise, is due to uneven mechanical equipment operation, mechanical shaft concentricity deviation, the size deviation between components or appearance defects and crash into each other, alternating mechanical force produced by the friction equipment sheet metal, bearings, gears and other moving parts fit vibration and radiation noise source called machinery noise. Here we illustrate them one by one to clarify all kinds of mechanical equipment noise. Friction noise objects in certain contact with each other under the action of movement, the friction between the object and the friction to reverse direction on the contact surface on the moving object, thus draw the object vibration and noise. Such as the voice of the underground train braking. Friction noise is the main friction the relaxation of the object of noise and vibration when the vibration frequency and natural vibration frequency of the phase object at the same time, the friction noise will reach the maximum. The impact noise because of the action of impact mechanical causes strong impact noise. Such as forging hammer the mechanical energy can be divided into four partial at work, the first local work, the second partial is converted into heat energy, the third local after roots spread into the surrounding air, in the form of solid sound local is converted to make 4 parts can produce the vibration of elastic deformation. Parts can elastic deformation vibration of a local again into the surrounding space radiation in the form of sound waves, constitute the impact noise, the noise will also be able to synthesis for radiation noise, pressure produced by the impact for the impulse noise and structural noise. With the impact of structural noise is the largest, longest radiated noise. Impact noise has the following characteristics: when collision attack in a hard lubrication between objects, the role of time is short, the force is big, is encouraged by the wide band, creating mode of vibration is much object itself a wideband noise impact; If hit attack in soft lubricated between objects, action time is relatively long, small forces, encourage the narrow frequency band, has less vibration mode. Construction machinery noise is forced vibration due to mechanical vibration system and natural vibration provoked together, one of the natural vibration played a leading role, natural vibration frequency is the main component of noise, and the natural vibration frequency of the vibration system depends on the structural characteristics and parameters of system, the so called this kind of noise is the construction noise. Any mechanical parts has its inherent vibration mode, different mode of vibration corresponds to different vibration frequency. The mode of vibration, frequency, and the structure of the parts or the physical properties of materials, parts and vibration shape of the border conditions. Material of the modulus of elasticity is larger, the more data thick, thick, its inherent frequency is high; Data area is larger, the more long, the greater the plate area, its inherent frequency is low. Gear meshing of gear noise or gears, because of a collision or friction may arouse the vibration of the gear body, radiate the condition of noise claims for gear noise. Stir up ordinary noise produced by periodic force of rotating machinery. The simplest periodic force is the axis of rotation, the flywheel rotating system of static and dynamic imbalance provoked by the eccentric force. The quality of this force is proportional to the rotation system and static and dynamic synthesis eccentricity, also will be proportional to the square rotation velocity. When the speed of the rotation system reached its critical speed, the system itself will produce great vibration, and vibration power transferred to the connected with other mechanical local, provoked a fierce noise. Provoked a noise as part the presence of cracks, structural stiffness or friction increases with serious enough. Bearing noise bearing inner relative motion between the parts of the friction and vibration, or turn the local imbalance ( Performance in different heart) under the condition of shaft , relative motion between the parts of impact, etc. , will incur bearing noise.