What is a gear coupling?
The gear coupling is composed of an inner ring gear with the same number of teeth and a flange half coupling with outer teeth. External teeth are divided into two tooth shapes: straight teeth and drum-shaped teeth. The so-called drum-shaped teeth are made of spherical surfaces. The center of the spherical surface is on the gear axis. The tooth side clearance is larger than that of ordinary gears. Larger angular displacement is allowed (compared to spur couplings), which can improve the contact conditions of the teeth, improve the ability to transmit torque, and prolong the service life. When the gear coupling is working, the two shafts produce relative displacement, and the tooth surfaces of the inner and outer teeth periodically slide relative to each other in the axial direction, which will inevitably cause tooth surface wear and power loss. Therefore, the gear coupling needs to be well lubricated and sealed. work in the state.
The gear coupling has a small radial dimension and a large load-carrying capacity. It is often used in shaft transmission under low-speed and heavy-duty conditions, such as metallurgy, mining, and lifting and transportation industries. It is also suitable for petroleum, chemical, and general machinery industries. High-precision and dynamically balanced gear couplings can be used for high-speed transmission, such as shaft transmission of gas turbines. Since the angular compensation of the drum-shaped gear coupling is greater than that of the straight-toothed coupling, the drum-shaped gear coupling is widely used at home and abroad, and the straight-toothed coupling should not be used as much as possible.
The characteristics of the gear coupling:
The gear coupling has a small radial size and a large bearing capacity, and is long used for shaft transmission under low-speed and heavy-load conditions. High-precision and dynamically balanced gear couplings can be used for high-speed transmission, such as the shaft of a gas turbine. Department of transmission. Because the angular compensation of the drum-shaped gear coupling is greater than that of the straight-toothed coupling, the drum-shaped gear coupling is widely used at home and abroad, and the straight-toothed Choose.
The more common gear couplings in the market include general structure gear couplings, drum type gear couplings, nylon gear couplings, etc. Among them, the drum type gear coupling has many models and is widely used.
Classification and characteristics of gear couplings:
The gear coupling can be divided into three types according to the axial tooth shape of the outer gear sleeve, namely straight tooth coupling, drum gear coupling and special drum gear coupling. No matter which one, the internal ring gear and the involute spur internal gear are all the same except for the selection of the top clearance coefficient of the gear teeth.
The axial gear blank of the outer gear sleeve of the straight tooth coupling can be processed into two types: straight line and arc shape, while the index circle and dedendum circle are both straight lines. The meshing form of this coupling and the gradual The meshing of the internal and external teeth of the open-line cylindrical gear is exactly the same. The relative displacement between the two shafts is compensated by increasing the backlash of the internal and external teeth, but the amount of compensation is limited.
The tooth top of the outer gear sleeve of the drum-shaped gear coupling is processed into a circular arc, that is, the tooth blank is processed into a spherical surface. In the section of the tooth center plane and tangent to the pitch cylindrical surface, the teeth form a drum shape, which is the so-called drum shape. coupling. Its characteristics are:
1. High bearing capacity. Calculated by bending strength, under the same conditions, the torque transmitted by the straight-toothed gear coupling is 15-30% higher;
2. The structure is reasonable and the performance is reliable. Because the tooth side is in a drum shape, the contact condition of the axis is improved under a certain angle condition, thereby reducing the contact stress and eliminating the load concentration at the tooth end of the spur coupling, that is Edge pinching is eliminated, improving workability.
3. The compensation performance is good. The tooth shape of the outer gear sleeve is drum-shaped, which increases the relative offset allowed by the two connected axes. The allowed inclination angle can reach up to 6 degrees, and generally recommends 1.5°～2.5°.
Overhaul method of gear coupling:
There are hundreds of varieties of gear couplings, but there are two basic forms: 1. Combination of internal teeth and external teeth; 2. Combination of end-face teeth. All other forms are variations on these two foundations. The tooth clutch with internal teeth and external teeth has relatively large transmission torque. The different needs of users are considered in the design, and the lengths of the shaft ends on both sides of the teeth are intentionally designed to be inconsistent, so that users can choose the installation direction according to their needs. Therefore, there is no rule as to which end faces where. Pay attention when installing: 1. If it is replaced on the original equipment, it should generally be in the same direction as the original one. If it is a newly designed and manufactured equipment, it should be installed according to the inner and outer directions without interfering with other surrounding parts. The more tooth joint surfaces, the more reliable the installation principle.
The overhaul of the gear coupling is generally carried out as follows:
1. Check the meshing condition of the tooth surface of the coupling. The contact area is not less than 50% along the tooth height and not less than 70% along the tooth width. The tooth surface must not have serious pitting, wear and cracks.
2. The full circular runout of the outer ring gear of the coupling is not greater than 0.03mm, and the circular runout of the end face is not greater than 0.02mm.
3. If the ring gear needs to be removed, special tools must be used instead of knocking, so as not to bend or damage the shaft. When reassembling, the ring gear should be heated to about 200°C and then installed on the shaft. The interference between the outer ring gear and the shaft is generally 0.01~0.03mm.
4. When reassembling the intermediate sleeve or other parts, it should be assembled according to the original marks and data.
5. Tighten the bolts evenly with a torque wrench.
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