With the rapid development of modern machinery industry, in some areas has put forward higher and higher requirements of gear transmission noise index (such as noise indices of some types of three stage planetary gear reducer is 52dB), especially in the DB value reached under the condition of no noise problem is also proposed. After years of hard work and unremitting practice, we made some valid measures of reducing gear transmission noise.
To ensure the quality of raw materials.
Materials of gear manufacturing is commonly used in 40Cr, 20CrMnTi, 40CrNi and other alloy steel and 45 steel. In order to ensure the quality of raw material, we adopt the method of fixed-point purchase, also is the purchase of Baosteel, Shougang, like Handan Iron and steel and other steel production of high-quality steel, to the factory after the chemical composition determination must pass strict inspection, grain size and purity assessment, its purpose is to facilitate the timely adjustment of heat treatment process, the control of heat treatment deformation, to improve the quality of cutting the profile of tooth.
Two. To prevent heat treatment deformation
Gear blank in rough machining or finish forging, should be to eliminate the residual stress normalized; normalizing or quenching and tempering treatment, must keep the furnace temperature uniformity, while using the jig, the work piece evenly heating and cooling; minimize the use of cyanide treatment, it than carburizing and quenching temperature is low, small deformation, and nitriding or carburizing than cheap, used for cyanide treatment equipment, must use the drip type UNIC gas carburizing nitriding furnace; part of the high frequency quenching and cyanide treatment gear device can also use soft nitriding process, in order to obtain high hardness and thick white layer.
Three. To improve the machining precision of gear blanks
1 to improve the machining precision gear hole: the size precision gear hole, the middle should be in the hole deviation values near the left and right distribution difference, generally set at 0.003 ~ ± ± 0.005mm, if ultra poor and in the holes of the design range, must be separately into cutting process, in order to take measures; at the same time, hole the line must be controlled within 0.003mm;
2 control of gear blank face runout and radial runout: end of gear blank is directly affect the tooth to beat the tolerances of the project, on the two end face processing gear blanks, must ensure that the parallelism within 0.01mm, and then on the tooling precision boring, to ensure that the hole on the end face runout; in cutting, must used by table 100% round the school, to ensure that the gear ring radial runout tolerance.
Cutting measures in four.
1 gear cutter: the outsourcing of gear cutter, all inspection, must reach AA level requirements, are not up to the requirements of gear cutter, shall all the fine grinding; the gear cutter all used Dutai processing, improve the tool endurance, improve the top part of the cutter wear, preventing gear root circular arc is too large; the m=0.3 - 0.8 by top gear hob; m=1 ~ 2 gears with addendum modification circular hobbing cutter, rounding amount of R=0.1m ~ 0.15m; improve the gear tooth top interference, in does not affect the strength of the gear case, increase the addendum coefficient, increase (0.05 ~ 0.1) m; improve tool tooth top durability, avoid gear tooth root interference.
2 machining process: cutting equipment to carry out a precision inspection by the mobile department every year, not up to the requirements must overhaul, especially the radial clearance of machine tool spindle should be controlled below 0.01mm, the knife shaft diameter jump below 0.005mm, the cutter shaft from moving below 0.008mm, cutter diameter jump controlled below 0.003mm, end jump 0.004mm the following; gap II cutting tooling the outer diameter of the mandrel and workpiece hole shall be guaranteed within 0.001 ~ 0.004mm; screw mandrel must be two and the top location, processing by the thread grinding to ensure verticality, ≤ 0.003mm, jump ≤ 0.005mm; tooling and nut must ensure that the internal thread and the reference surface a clamping car washer, parallelism to ≤ 0.003mm; gear parts processing good must pass through the evaluation of full-time inspectors, inspection projectFw、Fr、Fi″、fi″、Fβ、Ff。
Five machining after heat treatment.
1 for gear hole soft nitriding and teeth of high-frequency quenching, heat treatment using former volume method, heat treatment after research method of hole, to ensure machining precision and reduce the cost of production;
2 for gear hole cyaniding, hole grinding technology used for dividing circle positioning, Archimedes helix locking.
Six adhere to the civilized production.
According to statistics, there are more than 30% gear transmission noise causes from burrs and bump. In order to solve this problem, we adopt the following measures: gear processed all adopt the jig transport; gear shaft gear hobbing, immediately set up a plastic tube to the next working procedure, and with plastic casing delivery; gear parts cyanide treatment subject to the liquid sandblasting, and honing process at the same time, to remove the burr, and improve the tooth surface roughness and machining precision.
Due to the adoption of effective measures, unit production protection, civil gear box in each inspected, gear transmission noise indicators of all standards, has been generally praised the user side. After mass production practice over the years has proven, these measures is desirable, the effect is obvious.