What do the positive and negative represent? How did you get it?
(6) the old gear gear repair worn, small gear wear heavy gear wear light, can use negative shift to large gear tooth wear part cut and then use heavy with a positive displacement gear, materials and processing fees need this saves time for repair.The basic principle of choosing the coefficient of displacement(1) better lubrication gear when the gear surface hardness is not high (HBS < 350), the tooth surface without carburizing, nitriding, surface quenching hardened gear tooth surface pitting or peel injury is the main failure form, you should choose a total change as far as possible the coefficient of X, which try to increase the radius of curvature of the meshing angle, so as to increase the mesh node profile, reduce the contact stress, improve the strength and fatigue life of contact.When the tooth surface of high hardness (HBS > 350), often due to expansion of fatigue crack in the tooth root cause tooth fracture and makes the transmission failure, then select the modification coefficient of gear tooth bending strength should be increased as much as possible, and try to make the two gear meshing with similar bending strength.
(1) reducing the structure size and reducing the weight of the gear drive; under the condition that the drive ratio is certain, the gear tooth number ZL < Zmin can be reduced, so that the structure size of the transmission is reduced, and the weight of the mechanism is reduced.(2) to avoid undercutting, improve the bending strength of tooth roots when the number of gear teeth Z1 < Zmin, can use is changed to avoid undercutting, improve the bending strength of tooth root. X = xmin= (Z-Zmin) of /Zmin, alpha =20o, Zmin=17. (3) to improve the contact strength of tooth surface, the contact strength of tooth surface can be improved because of the increase of the radius of curvature of tooth profile when the meshing angle "alpha" is increased.(4) improve the tooth surface of the anti scuffing and wear resistance capability of the meshing angle alpha '> alpha positive drive, and proper distribution of variable coefficient XL, X2, the largest of the two gear sliding rate are equal, which can not only reduce the tooth surface contact stress, but also can reduce the sliding between teeth to raise the rate of gear anti adhesive and abrasion resistant ability.(5) with the center distance, when the number of teeth Z1 and Z2 remain unchanged, the meshing angle is different, and different center distances can be obtained, so as to achieve the purpose of matching the distance between the centers.
The deflection coefficient X is the radial displacement coefficient. When machining the standard gear, the center line of the gear bar tool is tangent to the gear indexing circle. When machining the modified gear, the tangent line between the center line of the gear bar cutter and the gear indexing circle is offset XM, the outer shift x is positive, and the inside shift x is negative. In addition to bevel gears, which sometimes use tangential displacement XT, cylindrical gears generally use radial deflection only.The choice of displacement coefficient X is not only to cut the center distance, but to improve the strength and the quality of transmission. The main functions of the shifting gears are as follows:
Yes, Xn stands for the normal coefficient of deflectionX stands for the coefficient of displacement, and X2 represents the coefficient of modification of the worm gear
