Gear transmission system of screw jack, which involves the whole process of design, manufacture, installation, maintenance, and update of gear transmission, demands many designers, manufacturers, installers and maintain-ers the rich knowledge reserves. NOSEN would have a brief passage for the design of the gear transmission.
Accuracy class of gear
When system designed, designers often consider the economical factors and the accuracy class was determined after economy. It is ignored that the accuracy class is related to noise and backla-sh of gear. The American Gear Manufacturing Association, has found that the high -precision gear operated with less noise than those of low-precision via numerous studies. Therefore,in cond-itions permitting, the accuracy class of gears should be increased to reduce gear noise and trans-mission errors possibly.
The width of gears
Increasing the tooth width can reduce the unit load under the constant torque. Noise could be reduced by the reduction of tooth deflection and noise excitation. Study arranged by H. Opats from Germany shows that when the torque is constant, the small width owns a higher noise curve than those wider. Similarly, the wider tooth can increase the bearing capacity of the gear.
Pitch and pressure angle
The fine pitch can ensure a larger contact, which increace the overlap of the tooth and reduce the single deflection to denoise and improve precision. Smaller pressure angle due to the larger contact of gear contact angle and the overlap ratio, which achieves a lower noise and higher prec-ision.
Study shows that the use of cylindrical box is advantageous for shock absorption. Under the same conditions, the noise level of the common structural gear box is averagely 6 dB higher than that of cylindrical box. Resonanc-e testing of gearbox helps to find the resonant position and add ribs (plates), such solution can significantly redu-ce vibration and noise. In the multi-stage gear transmission, the change of the instantaneous transmission ratio is required to be as small as possible to guarantee the stable movement,the small impact and vibration and the low noise.
Analysis of coustic radiation
When selecting different structural gears, an acoustic radiation model should be established for the specific stru-cture, then dynamic analysis should be performed to pre-evaluate the noise to meet the different requirements of the user (the place of use, whether it is unmanned, in the urban area, specific requirements for the above-ground and underground buildings, noise protection, or no other specific requirements).