helical gear intruduction and classification
Helical gears are not exactly sprial gears. It should be said that helical gears are the meshing mode of two helical gears, which are distinguished by the different directions in which they transmit forces in space. Ordinary spur gears are meshed at the same time along the width of the teeth, which results in shock vibration noise and unstable transmission.
Formation principle
The formation of the helical cylindrical gear tooth surface is shown in Figure 8.25.
In Figure 8.25, the generation surface is tangent to the base cylinder, and the generation line forms an angle βb with the axis.
When the angle βb = 0, the tooth surface of a spur gear is formed.
Geometric Parameters of Helical Cylindrical Gears
The end tooth profile of the helical cylindrical gear is an accurate involute, and the normal tooth profile is an accurate involute, as shown in Figure 8.27. Its end face and normal face parameters are different.
(1) The helix angle on the cylindrical surface of the base and the helix angle on the graduated circle
(2) Normal-face modulus mn and end-face modulus mt of a helical spur gear
(3) Normal surface pressure angle and end face pressure angle of helical spur gear
(4) Tooth height coefficient and root height coefficient of helical gear
(5) Helix angle on the cylindrical surface of the base and the helix angle on the graduated circle
(6) Correct meshing conditions of helical helical gear transmission
The relationship between the modulus, pressure angle and helix angle of a pair of helical cylindrical gears is
Equivalent gear of helical spur gear
Coincidence of Helical Cylindrical Gear Transmission
The upper left figure is the meshing surface of the spur gear drive, and the lower left figure is the meshing surface of the helical gear drive. B2B2 in the figure represents the position where the pair of gears enter the meshing position, and B1B1 represents the position where the gears are out of meshing.
Characteristics of Helical Cylindrical Gear Transmission
Advantages:
1) Good meshing characteristics,
2) Large coincidence
3) The minimum number of teeth that do not cause undercutting is less than that of straight teeth.
Disadvantage: Axial force is generated during work.
Staggered shaft helical gear drive
When two helical gears have the same normal modulus, the normal pressure angles are equal, and the helix angles are not equal, they form a staggered shaft drive. Their working tooth surfaces are in point contact.
(1) Center distance a = (d1 + d2) / 2 = mn (Z1 / cosβ1 + Z2 / cosβ2) / 2
(2) Transmission ratio i12 = ω1 / ω2 = Z2 / Z1 = (d2 / mt2) / (d1 / mt1) = d2cos β2 / mn2 / (d1cos β1 / mn1) = d2 cos β2 / (d1 cos β1)
Related parameters
Pitch circle diameter
Root circle diameter
basic introduction
The gear is made of high-quality and high-strength alloy steel, and the surface is carburized and hardened. The bearing capacity is strong and durable.
Product Categories
1.Involute helical gear reducer
The involute helical gear reducer has the characteristics of small size, light weight, high bearing capacity, high efficiency, long service life, easy installation, wide power range of the motor, and fine transmission ratio classification. Can be widely used in various industries requiring slowdown equipment.
2. Helical gear worm reducer
The helical gear worm gear reducer adopts a direct-connected form of the motor, and the structure is a first-stage helical gear and a first-stage worm and worm drive. The output is shaft-mounted and has six basic installation forms. It can run in both forward and reverse directions. The helical gear adopts a hard tooth surface, which runs smoothly and has a large bearing capacity. The working environment temperature is -10 ℃ ～ 40 ℃. Compared with similar products, this product has a wide range of speed changes, a compact structure, and easy installation. Can be widely used in metallurgy, mining, lifting, light industry, chemical industry, transportation, construction and other machinery and equipment of the reduction mechanism.
Features
Advantages and disadvantages of helical gears:
1 Because the meshing surface is from small to large, small, smooth meshing, small impact and low noise;
2 large carrying capacity, improve life and stability;
3zmin is small and difficult to undercut, small volume;
4 but the axial thrust is large, herringbone gear-no axial thrust, but manufacturing trouble.
Helical gear transmission is composed of two helical gears meshing. Uses: To transfer the motion between two phases in the wrong axis in space. Features:
1 spiral direction can change the center distance, transmission ratio
2 Steering can be changed by spiral rotation change
3Fast wear
4-point contact
5 small axial force
advantage
(1) Good meshing, stable transmission and low noise.
(2) The degree of coincidence is large, which reduces the load of each pair of gears and improves the bearing capacity of the gears.
(3) The minimum number of teeth without undercutting is small.
Disadvantage
(1) Herringbone gear manufacturing is troublesome.
Quenching
Quenching is to heat the workpiece to a temperature above the critical temperature Ac3 (hypoeutectoid steel) or Ac1 (hypereutectoid steel), hold it for a period of time to fully or partially austenite, and then cool it faster than the critical cooling rate A heat treatment process for cooling martensite (or bainite) below Ms (or isothermal near Ms). The purpose is to greatly improve the rigidity, hardness, wear resistance, fatigue strength and toughness of the workpiece.
After hardening heat treatment, the surface of the helical gear will have a hardened layer. It is because of this hardened layer that the hardness, wear resistance and service life of the helical gear are greatly improved.
