The spur gear rotary drive consists of a slewing bearing, gears, housing, adapter flange, support bearing, seals, and other components. Below, Buer Transmission will introduce each component in turn.
1. Slewing bearing
Slewing bearings typically employ a four-point contact ball bearing design, capable of simultaneously bearing axial and radial loads as well as overturning moments, and operating at high speeds. For customers with special operating conditions, such as high overturning forces, high impact, or high vibration, crossed roller or three-row roller slewing bearings may be used, depending on the specific circumstances.
The slewing bearing is made of 42CrMo forgings that have undergone tempering (Q+T) treatment to achieve a hardness of 229-269HB. After tempering, the mechanical properties are greatly improved, and the load-bearing capacity of the slewing bearing is also increased.
The slewing bearing groove is induction hardened to a hardness of 55±5HRC. The groove surface is hard and the core is soft. After quenching, the groove has strong load-bearing capacity, is strong and wear-resistant, has good toughness and excellent impact resistance.
The slewing bearing teeth are also induction hardened to a hardness of 50±5HRC. After hardening, the teeth also have the characteristics of hard surface, soft core, strong load-bearing capacity, strong wear resistance, good toughness, and excellent impact resistance.
The geometric accuracy, rotational accuracy, and clearance of a slewing bearing are determined based on the customer's specific application requirements. If the user requires a slewing drive with standard precision, a slewing bearing with standard precision needs to be designed and manufactured according to the national standard P0 grade. If the user requires a precision slewing drive with high precision, a precision slewing bearing needs to be designed and manufactured according to the national standard P5 grade. If the user requires an ultra-high precision or gear-type slewing drive with special requirements, a slewing bearing with ultra-high precision that also meets the user's special requirements needs to be designed, such as zero clearance, negative clearance, strict end runout requirements, or tooth runout requirements ≤0.05mm. Special processes need to be developed to meet these requirements.
2. Gears
The gears are made of 42CrMo forgings that have undergone tempering (Q+T) treatment, resulting in a hardness of 229-269HB. After tempering, the mechanical properties are greatly improved, and the load-bearing capacity of the gears is also increased.
The gear teeth are induction hardened to a hardness of 50±5HRC. After hardening, the teeth also have the characteristics of hard surface, soft core, strong load-bearing capacity, strong wear resistance, good toughness, and excellent impact resistance.
The gear shaft bore is used to mate with the customer's reducer or motor shaft to transmit kinetic energy. The tolerance of the shaft bore fit with the customer's shaft is very important; a sliding fit is generally used. The gear shaft bore is finally precision ground to ensure the fit dimensions. The gear shaft bore is designed according to the output shaft drawing of the reducer or motor selected by the user. When assembling the equipment, the user can directly install the reducer or motor shaft into the gear shaft bore, which is very convenient and reliable.
The gear adopts a universal bearing end-support design, which does not rely on the support of the reducer shaft or motor shaft and can rotate independently. The end-support design allows the gear to withstand very high radial forces. When used under large impact loads or large inertia conditions, it has high reliability. Compared with gears that rely on the reducer shaft or motor shaft for rotation, it can effectively reduce the damage to the reducer shaft or motor shaft, reduce the failure rate, improve equipment reliability, and reduce maintenance costs.
3. Shell
The shell is made of ductile iron QT450-10, and the carbon in QT450-10 is in the form of spherical graphite.
Tensile strength σb (MPa): ≥450
Yield strength σ0.2 (MPa): ≥310
Its mechanical properties are close to those of steel and far superior to those of gray cast iron.
Elongation δ (%): ≥10
Hardness: 160～210HB
After casting, normalizing treatment improves plasticity and toughness, enhancing overall mechanical properties. It exhibits excellent castability, minimal processing deformation, high strength, wear resistance, stability, and durability.
Designers should continuously optimize the shell casting drawings to avoid unnecessary casting deformation. Based on the actual situation during the machining process, they should appropriately adjust the shape of the casting and the machining allowance. During the machining process, the machining steps required by the process must be strictly followed. The machining steps must not be reversed, and the machining parameters must not be changed without authorization. The key mating dimensions must be well controlled. Only in this way can qualified shells be machined efficiently and with high quality.
4. Fitting flange
The adapter flange is a crucial component that connects the upper and lower parts of the gear assembly. One function of the adapter flange is to secure the gear to the housing, ensuring its independent and stable rotation. The other function is to serve as the input end of the gear-driven rotary drive, connecting to the output flange of the user's reducer or motor. Given the functional characteristics of the adapter flange, custom-made flanges are a better choice. The adapter flange is designed according to the output dimensions of the user's selected reducer or motor, while also accommodating the gear mounting function. During the design process, special situations often arise, such as flange interference with connection holes, flanges that are too large, and difficulties in arranging flange bolts. This requires designers with extensive experience to solve practical problems based on the specific circumstances.
5. Support bearing
The support bearing for spur gear rotary drives is a general-purpose bearing that supports gear rotation. The selection of general-purpose bearings is based on specific operating conditions, taking into account the characteristics of various bearings and their performance parameters such as load and speed. Commonly used bearing types include: angular contact ball bearings, tapered roller bearings, cylindrical roller bearings, and deep groove ball bearings.
6. Sealing
The seals of gear-type rotary drives typically use NBR oil-resistant nitrile rubber seals. The slewing bearing grooves are sealed, and the slewing bearing and housing are also sealed. This ensures that the rotating lubrication parts of the gear-type rotary drive are dustproof and waterproof, which can effectively reduce the maintenance frequency of the gear-type rotary drive and lower the failure rate.
