Maintenance method and design optimization problem of drum gear coupling

The drum gear coupling is one of the basic parts of the machinery industry. It is mostly used in the transmission of heavy loads, high efficiency, and large adjustment errors and deviation angles of the two coupling shafts.The gear teeth of its outer gear sleeve are arc-shaped along the length direction, while the gear teeth are drum-shaped when viewed from the top of the tooth, that is, on the same tangent plane parallel to the axis, the tooth thickness gradually changes from the middle of the tooth length to both ends Reduced, and the tooth profile of the inner ring gear meshing with the outer gear sleeve is linear.Because the tooth top surface and the tooth flank of this kind of external gear sleeve are both arc-shaped (this is different from the characteristics of the ordinary gear coupling), the entire coupling becomes a double joint and is flexible.Due to its structure, the drum gear coupling has the following characteristics: ① It can compensate the deviation of angular installation and radial installation due to the non-coincidence of the two coupling axes, and it can be driven in the horizontal direction or Under the special structure, vertical transmission, ②compact structure, low weight and moment of inertia, ③because all parts are circular, so the unbalanced moment is small.

Based on the above characteristics, drum gear couplings are widely used in metallurgy, mining machinery and other industries.In particular, the main rolling mill shaft and coupling of the large-scale cold and hot strip continuous rolling mills introduced in recent years all use drum-shaped teeth.This article will explain the optimization problem of drum gear coupling design.

The bearing capacity and allowable offset or swing angle of the drum gear coupling are directly related to the radius of curvature (curvature) of the tooth.From the perspective of increasing the load-bearing capacity, the larger the radius of curvature, the better; and in terms of increasing the allowable swing angle, the smaller the radius of curvature, the better.The arc of the drum tooth surface is naturally formed when the hob moves along the arc during machining, so the radius of the infeed arc determines the radius of curvature of the tooth.

In order to find the relationship between the radius of curvature of the drum tooth surface and the radius of the indexing arc, it is necessary to find the normal and tangent radius of curvature of the drum tooth surface on the indexing circle.

In the design of drum gear couplings and shaft couplings, the correct tooth flank clearance is first given when calculating the geometric dimensions.Because even though the arc-shaped teeth are used, the radius of curvature of the arc cannot be too small due to the load strength. If there is not a sufficient amount of tooth side clearance, the phenomenon of gnawing will occur when there is an angular deviation.What this article recommends is the method of selecting and reasonably distributing the side clearance of the outer gear bushing and the inner gear ring.

The drum gear coupling has its unique advantages in intermittent, reversible, high-load, high-speed mechanical transmission, especially in transmissions with large adjustment errors and deflection angles between the two coupling shafts. , So it is widely used in all kinds of metallurgy and mining machinery.The optimized design method described in this article has been incorporated into our company's standards, and has been widely used in the design and manufacture of various related complete sets of equipment, and has achieved very satisfactory results.

High-speed drum gear couplings are usually lubricated with lubricating oil. The tooth surface requires continuous lubrication, and the lubricating oil drain should be smooth, otherwise the temperature of the tooth surface will increase and moisture and dirt will accumulate.The lubricating oil needs to be filtered by a high-precision oil filter with a filtration degree of less than XNUMXμm.Some important high-speed drum-shaped gear couplings can also adopt the structure of oil collecting groove holes. The Liaocheng drum-shaped gear coupling, that is, the oil collecting groove is machined in the outer gear shaft hole, and the oil collecting groove is drilled and collected at the bottom of the outer gear tooth groove. The oil holes in the oil grooves use the centrifugal force generated by the high-speed operation of the drum-shaped gear coupling to spray oil into the meshing parts of the inner and outer teeth to make them fully lubricated.

The torque drum gear coupling has good impact bearing performance, but the tooth surface contact stress and tooth root bending fatigue strength require high requirements. If we adopt special structure, special materials, and special processes, then the coupling can meet the requirements of large diameters. The requirements of the rolling mill.

Maintenance method of drum gear coupling:

1. Check the tooth surface meshing of the drum-shaped gear coupling. The contact area along the tooth height is not less than 50%, and the tooth width is not less than 70%. The tooth surface must not be severely corroded, worn or cracked.

2. The full circle runout of the outer gear ring of the drum gear coupling is not more than 0.03mm, and the end circle runout is not more than 0.02mm.

3. If it is necessary to remove the gear ring, use special tools and do not knock, so as to avoid bending or damage to the shaft.When reinstalling, heat the ring gear to about 200°C before installing it on the shaft.The interference between the outer gear ring and the shaft is generally 0.01~0.03mm.

4. When reinstalling the intermediate tube or other parts, it should be assembled according to the original markings and data.

5. Tighten the bolts evenly with a torque wrench.

What are the requirements of the drum gear coupling for the drum curve? The drum tooth surface of the non-conjugated tooth surface is formed by gradually displacing the different end sections. The dashed line formed by the displacement and the axial coordinate is called the drum. Degree curve, drum degree curve is an important geometric parameter of drum gear coupling.The bulge curve is mostly an arc, and there are also three arcs. These circles are called bulge circles. In the arc bulge curve, there are bulge circles on the axis of the gear, and others not on the axis; The drum circle coincides with the spherical surface of the tooth surface, and some do not. Usually the design is based on experience. In general, the drum gear coupling should meet the following requirements:

No edge contact occurs when the inclination angle between the shafts is large;

The smaller the gear tooth concentrated load is, the better, and the curvature of the tooth surface is proportional to the circumference of the drum, so the drum radius is as large as possible.The curvature radius of the bulge curve is proportional to the single-sided thinning of the internal tooth, so the bulge circle radius should be as large as possible.The radius of curvature of the bulge curve is proportional to the single-sided thinning of the internal tooth, that is, it is related to the meshing gap of the tooth. Insufficient thinning may cause interference, and excessive thinning will weaken the strength of the tooth, and the backlash will be large. .