Causes and control methods of hoist noise
Construction hoist GB1955-2002 national standard GB 1955-2002 qualified winch noise limits outside the machine are not greater than 85dB (A), the operator cannot be greater than the ear 88dB (A). When the hoist traction is small, the speed is low, the noise is far below the standard limits, the control is also easy; but when the traction speed is high, to ensure that the traction is not excessive noise, from the design, technology, materials, quality Inspection and other links to take effective measures.
There are many ways to get the noise of hoist, but in essence, it is the result of impact and vibration, which is usually caused by the poor gear meshing quality and unstable motion.
We believe that the chassis design and manufacture are caused by noise may be: the chassis adopts box type structure, not all welds are continuous welding, the weld length, different chassis height, there exist great individual differences in chassis rigidity, others resonate effect, machines such as a little vibration noise is amplified; the chassis is made of steel plate welding, do not have the shock absorption, noise elimination function, if close to the natural frequency and the meshing frequency may cause the individual machine for small gear vibration caused greater total shock caused by noise value rise.
we in view of the above possibilities are tested, but by three experiments showed weak correlation factors of noise level and chassis structure, stiffness, frequency, noise and moving parts strongly correlated, so the chassis structural design, manufacturing quality and not exceed the standard noise causes.
It is believed that since the noise is accompanied by a drum assembly and a transmission, it may be caused by the large clearance of the roller bearing. We choose the clearance of the reel parts to ensure that the clearance between the bearing hole and the spindle is in accordance with the requirements of the drawing, and the test is carried out after the assembly is assembled. Frequency conversion motor is used in the test to observe the influence of speed on noise.
A large number of test results show that the influence of speed on noise is the first. The higher the speed of the drum, the greater the noise and the more intense the machine vibration. Secondly, the larger the gap between spindle and bushing, the greater the noise. The chassis has the least influence on noise. If the machine noise is very low, the speed and the size of the spindle gap will not generate excessive noise, which indicates that the excessive noise is not caused by the large bearing clearance.
After the inspection of gear common normal length tolerances, the base tangent length of radial gear tolerance, runout, drum related coaxially and the spindle shaft neck beating control indicators are within the scope of the standard specification, but on further examination found to exceed the standard gear tooth profile error, the reason is hob grinding. Because it is a large modulus cutter, cut and processed materials, roll cutting resistance of cutting-edge, easy blunt, with a number of parts processing midway may need one or two knives grinding, such as grinding rake hob tooth profile control is not good, easy to deformation, while the processing is no longer the standard involute tooth profile and the instantaneous acceleration produces motion, motion instability will inevitably generate vibration and noise.
winch as a general precision products, in the implementation of new standards for gear accuracy did not paid much attention to the inspection of tooth profile error, many units which are not indicators of detection equipment, so even if the drawings made this request in the actual test operation is not very good, although the length of normal line, change tolerance and ring gear jump targets to meet the requirements, but the gear is still unqualified.