The point line meshing gear is a new type of gear. The point line meshing gear transmission is a pair of concave and convex tooth profiles machined by an involute hob. It not only retains the advantages of the involute gear: it is easy to manufacture and manufacture. Divided; also has the characteristics of arc gear: high contact strength. Compared with the conventional involute gear transmission, the point line meshing gear transmission has a series of advantages such as large bearing capacity, high strength and low noise.
The point line meshing gear is further divided into a single point line and a double point line gear according to the shape of the tooth profile, and is divided into a medium hard tooth surface and a hard tooth surface gear according to its hardness. Among them, single-point line gears are widely used. In this paper, the single-point line medium hard-tooth point-point gear mesh gear reducer is used for experimental research.
1 Medium hard tooth surface single point line meshing gear transmission test 1.1 Test gear parameters The modulus of the medium hard tooth surface point line meshing gear is the same as the modulus of the hard tooth surface of the involute gear, and the helix angle is also close. The total gear ratio remains the same.
1.2 Installation method and test conditions The test bench is an open test bench. The test conditions are: N220 medium extreme pressure gear oil for lubricating oil; no cooling measures for gear box.
1.3 Test record 1) Noise measurement First measure the no-load noise when the motor starts, and then connect the test box to 9 points to get the no-load noise of the single-point line meshing gearbox is 67.88dB(A).
2) Carrying capacity test First run and run for 1~2h, with the rated power P=25.5kW of the hardened involute gearbox as 2 two-phase asynchronous motor (n=1500rmin, P=50kW); 22 torque speed Sensor; 32 single-point line medium hard-toothed gear test box; 42 involute hard-tooth test box; 52 load oil pump for full load loading power, then gradually load 50, 70, 100. After running at full load power for 10h, The low speed pinion has a full tooth length break and the test is aborted. The test data is listed.
Test single point line gear bearing power symbol contact fatigue bending fatigue power kWP25.5 rated power multiple K3.78 high speed shaft cycle number N9×1059×105 high speed shaft equivalent torque NmTd188.32134.07 high speed shaft power kWP13.8721.06 low speed shaft equivalent torque NmTd2367.8550.6 Low-speed shaft power kWP10.7516.11.4 Test results analysis 1) Test results The low-speed pinion has a full tooth length break, while the high-speed stage has no broken teeth, and the high and low speed tooth surfaces are not pitting.
2) Check the low-speed pinion material. The original design material is 42CrMo, and the inspection result is 40Cr, indicating that the bending strength formula of the single-point line meshing gear is correct, but it is conservative.
3) The high-speed bending strength is compared with the rated power of the hardened surface in the involute: K=21.066.6=3.19 times; compared with the involute hard tooth surface: K=21.0625.5=0.82 times; high-speed contact strength For the involute, the rated power of the hardened surface is K=13.876.6=2.1 times, which is 1.1 times higher.
2 In the test of the middle hard-tooth surface single-point line meshing gear transmission test, the modulus is the same as that of the involute hard tooth surface, and the helix angle is also close. When the high load test is used, the point line meshing gear is broken, so the increase is increased. The modulus is retested.
2.1 Test gear parameters Test gear parameters 2.2 Installation method and test conditions The test bench is open test bench 12YCT280 speed control motor; 22200Nm torque speed sensor; 32 single point line meshing gear test box; 425000Nm torque speed sensor; 52 increase Speedbox 1 (double-point line soft toothed gear and single-point line hard-toothed gear); 62 speed-increasing box 2 (involute hard-toothed gear); 72 hydraulic dynamometer test conditions and test.
2.3 Test Record The test was performed in 2 sessions. The first test: First run, and then measure the curve of no-load power loss.
1) No-load power curve when the reducer is not running 2) There is a small amount of load running, which increases with time. The load decreases and the efficiency increases.
3) Efficiency curve at different speeds under the same load (light load).
4) Efficiency curve at different powers at the same speed.
Loading and carrying capacity test, starting to load to 7kW, within the allowable stress value, after loading to 13.8kW, greatly exceeding the allowable stress value of the material. On the one hand, the temperature rise is as high as 40 °C. On the other hand, it is found that there is a little pitting on one end of the high-speed large tooth, and the load is immediately reduced to 7 kW, and the operation is performed 107 times. After the first test, the pitting of the high-speed large gear is partially pressed. Ping, no further development, no abnormalities in the remaining tooth surface.
During the inspection, it was found that both the high-speed pinion and the large gear were severely pitting but there was a flattening phenomenon. Some of the low-speed large teeth were flattened by the pitting, but the tooth surface of the small gear was not developed.
2.4 Analysis of test results 1) Open the lid of the test box and carefully check that the plastic deformation of the high-speed large gear is large, so the amount of thinning is large.
2) It can be seen from the test data that the contact strength of the point-line meshing gear is K=9.454.8=1.97≈2 compared with the involute gear, which means that the contact strength is slightly lower than that of the previous test. The reason is that the load is too large during the loading process, and the contact stress greatly exceeds the allowable stress value of the material, so pitting is quickly generated.
3) The test has a small helix angle, so the contact strength is small. Therefore, the contact strength is related to the parameter, and the calculation also reflects that the helix angle is small and the contact strength is high.
3 Conclusions 1) The efficiency of the new reducer can reach 96 or more, up to 97.
2) The contact strength has been tested and tested by the manufacturer Nanjing High Speed ​​Gearbox Factory, and its carrying power is 1.6 times higher than that of the involute gear. It is shown that the contact strength of the hard point surface in the point line meshing gear is 1.5 times higher than that of the involute gear, which is about twice the hard tooth surface in the involute line.
3) Bending strength point line The large gear of the gear pair is increased by more than 10 than the involute, and the calculation formula is correct and safe. When the dotted line meshing gear modulus is the same as the involute, it is about 3.2 times of the rated power of the hardened surface in the involute, and it is 0.85 of the rated power of the involute hardened gear with the same modulus. Times around. When the modulus increases, the value is exceeded.
4) With the increase of the load, the contact area of ​​the dotted line meshing gear increases, and the noise also decreases. It is 7dB lower than the involute condition.
5) When the point-line meshing gear is tested, the contact stress and bending stress should not exceed the allowable stress of the material. Otherwise, pitting and bending will occur quickly.
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