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Reliability-based gear reducer optimization design optimizes the gear reducer based on the reliability of the gear reducer. Considering the diversity of constraints and many uncertain factors in gear transmission design, In the mathematical model of the optimal design of the gear reducer with the lowest mass as the target, the reliability index is directly introduced into the constraint condition, which overcomes the optimization design of the conventional gear reducer and takes the static performance and the boundary constraint as the constraint conditions, without considering the reliability of the gear strength. Defects in sexual indicators. Therefore, the established mathematical model of reliability optimization design is more scientific and reasonable, and the gear meshing parameters and constraints are more in line with objective reality.
1 Establishing a mathematical model 11 design requires the design of a two-stage helical gear reducer as shown.
It is known that the input power P=301W, the first stage pinion speed, a two-stage helical gear reducer, =9801'/cylinder total gear ratio i=8, the gear machining accuracy is 8 grades.
It is required to obtain a reducer device with small volume and small mass under the condition of ensuring tooth surface contact fatigue strength, root bending fatigue strength reliability and geometric boundary constraint.
12 Determination of design variables in the secondary standard helical gear reducer, independent design variables are high-speed, low-speed gear module mi, m2; two pinion gears Z, Z2; helix angle Pi, tooth width coefficient Xl, X2; high-speed gear ratio /, for the simplified design, the two small gears (drive wheels) in the high and low speed stages take the same material, the two large gears (driven wheels) also take the same material, the material density is PiP1 3 to establish the target The function design requires that the volume and quality of the two pairs of helical gears be kept to a minimum when the conditions of use are met. Therefore, the objective function can be decomposed into the sum of the sum of the volume of the two pairs of helical gears and the sum of the masses, and the volume is mainly determined by the center distance and the tooth width. Then the objective function can be established as follows: Fmil(x)aPY is the weighting factor of the objective function. By adjusting the weighting factor, the main factors affecting the target can be highlighted. In the example, a= 05P=03Y=0.2, that is, the sum of the center distances of the two gears is decelerated. The volume reduction of the device plays a major role.
(2) The contact stress of the helical gear tooth surface should be less than the allowable value 111. 1234 represents the 1234 helical gear; ZEI is the elastic influence coefficient, check the mechanical manual; the absolute value of the transmission ratio; b is the gear width, take the two wheels Small value; %k is the contact fatigue allowable stress.
(3) The coincidence degree of the helical gear should generally be greater than the coincidence degree e of the helical gear, consisting of two parts, e, i is the end face coincidence degree, that is, the coincidence degree of the spur gear transmission with the same tooth profile of the helical gear face; bitanPimnZ. Jms20 is the additional coincidence degree.
22 Boundary constraints (1) The minimum equivalent tooth number of the helical gear without root cutting Zv> (2) The helical gear helical angle has a value range of Pi=8° (3) The helical gear tooth width coefficient generally takes X, =0 ( 4) The helical gear that transmits power should guarantee mn>2 2 Determine the constraint The bookmark4 constraint mainly includes static performance constraints, boundary constraints and reliability constraints. Among them, static performance constraints include gear contact strength limit, gear bending strength limit, coincidence limit, etc.; boundary constraints include spiral angle limit, tooth width coefficient limit, modulus limit, structural interference limit, etc. Reliability constraints include reliable Degree limit, etc.
(5) The gear ratio of the high and low speed gearboxes should meet the i= is the low speed gear ratio), and the total gear ratio is i=i1 Xi2. Therefore, the transmission limit is 21 static performance constraints. To reduce the size of the reducer, the hard tooth surface should be selected. Gears, ie tooth surface hardness >35 (HBS. For hardened gears, the interference should be limited according to the root bending (6) structure, and the condition of non-interference of high-speed large gears and low-speed shafts-n- /2> 0, namely: the design of the bending fatigue strength, and then according to the tooth surface contact fatigue strength check 11. (1) the helical gear surface modulus should be greater than the design value 111. 2 respectively represent the high and low speed drive; = 13 respectively represent 2 small The parameter on the gear (drive wheel); K, the load (7) pinion hardness should be higher than the big gear hardness. In general, the hardness is proportional to the density, that is to say the hardness of the material is higher than the density Low hardness.
The coefficient, depending on the working conditions, can take 1 ~ 24 and take the middle 16 . For the driving wheel torque; Yf, Ysi are the tooth shape coefficient and the stress correction coefficient respectively, check the mechanical manual, take the larger value of the two wheels; 23 gear reliability constraints due to the tooth surface contact stress and the tooth surface contact fatigue strength limit Obtained: log contact fatigue limit mean contact fatigue limit mean contact fatigue limit variation coefficient 2, 30 means there are 30 constraints in total, they are bound by gi0(x)g(x) 4 constraints plus g2 2 constraints Multiply by 4 (4 gears must meet the constraints), plus the remaining constraints multiplied by 2 (high and low speed gearing).
Table 1 Reliability Optimization Design and General Design Calculation Results Comparison Design Parameters Conventional Design Optimization Design It can be seen from Table 1 that under the condition of the same input speed and power, the reliability optimization design scheme is reduced by 15 8% compared with the conventional design scheme. The sum of the center distances is reduced by 123%, the sum of the tooth width coefficients is reduced by 167%, and the mass is reduced by 135%. The reliability of the strength conditions can meet the requirements, but the above optimal solution cannot be directly used as the design parameter of the reducer. The number must take the standard value. After verification, the optimal solution of the final reliability optimization design 5 Conclusion Based on the reliability optimization design, the mechanism is optimized on the basis of ensuring the reliability, which not only ensures the design organization has a certain working reliability but also greatly The organization has been optimized to a more reasonable structure, size, size and weight. The reliability-based gear reducer optimized design principle is simple, the algorithm is reasonable, and the result is ideal. It can be extended to other similar situations of mechanical design.
4 Reliability optimization results analysis and conventional design results comparison
In the die casting process,higher specific pressure is required, so that higher filling speed can be obtained.which is beneficial for alloy to overcome mold filling resistance.and effectively fill each part of the cavity.The Casting General Tolerance is Grade GB-CT4.
Process Technology: High pressure die casting, Cold Chamber
Product Dimensions: Customized
Casting General Tolerance: Grade GB-CT4
Flow Processes: Die casting, Degating to remove the residual of the gate, Polishing and Deburring to remove the burrs, Polishing to remove the parting line, flash,CNC Turning, Cleaning, Packaging, Storaging, Shipping
Control Measure: Incoming Material Test, First Article inspection, Routing inspection, Final item inspection, and Outgoing quality control
Inspection Equipment: CMM, Caliper, Plug Gage, Screw Gauge
Application: Machinery Parts
Certificate: IATF16949:2016,ISO14001:2015,ISO45001:2018
Lead Time: 30-35 days
Trade Term: FOB Ningbo