Structure and lubrication of head sheave device of multi rope hoist

The head sheave device is one of the important load-bearing components of the multi rope friction hoist. Its role is to support the steel wire rope between the friction wheel of the hoist and the lifting container, which is used to change the direction of the steel wire rope, that is, to guide. In recent years, with the continuous development of hoist technology, the manufacturing technology of head sheave ?device is also constantly improving.

The head sheave device is composed of fixed wheel, traveling wheel, head sheave ?shaft and main bearings at both ends, as shown in Figure 1. The fixed wheel is connected with the shaft through the flat key. When the hoist is running, the friction wheel drives the steel wire rope to move. The steel wire rope drives the fixed wheel to rotate through the friction between the steel wire rope and the head sheave ?liner, thus driving the head sheave ?shaft to rotate at the same time. When the linear speed of each wire rope is not completely the same, each traveling wheel and head sheave ?shaft can rotate relative to each other to eliminate the additional torque generated by the difference of the linear speed of each wheel.

1. Main bearing 2. Fixed wheel 3. Running wheel 4. Gasket 5. Rim 6. Bearing bush7. head sheave ?shaft 8. Spoke 9. Fixed hub 10. Traveling hub 11. Retaining ring

Figure 1 Structure of Conventional head sheave Device

1 Conventional structure

The head sheave device is generally of cast welded structure, that is, each wheel body is welded by the cast rim and spoke composed of hub and channel steel (see Figure 1). A copper alloy bearing bush with two lobes structure is installed between the inner hole and the shaft of each traveling wheel. The bearing bush and the traveling hub are fixed with end screws to make the bearing bush and the traveling wheel run at the same time. An oil filling hole is reserved on each traveling hub, so that the lubricating grease can be injected into the contact surface between the bearing bush and the shaft. As the bearing bush is a wearing part, in order to facilitate the replacement of the bearing bush at the use site, there is space for the axial movement of the bearing bush at one side of the head sheave ?device. When the bearing bush is damaged, the retaining ring can be removed first, and then the damaged half bearing bush can be removed from the axial direction for replacement. In the replacement process, each runner can be replaced in turn.

Some foreign hoisting machine manufacturers locate the hub and bearing bush of the traveling wheel by means of key connection, as shown in Figures 2 and 3. In order to facilitate the installation of keys, each wheel body of this connection mode is of two split structure.

Fig. 2 Key connection

Fig. 3 Double key connection

The above three structural forms coexist in the mine hoists used in China, which are mainly determined by the habits of different hoist manufacturers, and all belong to mature structures.

2 New structure

Rolling bearing is the most widely used component in mechanical equipment, especially in rotating machinery. For the head sheave ?device with new structure, rolling bearing is used at the inner hole of the traveling wheel to replace the copper bearing bush, as shown in Figure 4.

1. Flat key 2. Fixed wheel 3. Running wheel 4. Rolling bearing 5. Spoke

6. Fixed hub 7. Traveling hub 8. Shaft sleeve 9. Hub end cap

Fig. 4 Structure of new head sheave device

Two rolling bearings are respectively installed between the hub and the shaft of each traveling wheel as a support, and the axial positioning between the bearings is carried out through the shaft sleeve. When the linear speed of each wire rope is not exactly the same, each traveling wheel and the shaft can freely and flexibly rotate relative to each other through the bearing. An oil filling hole is reserved on each traveling hub, so that the lubricating grease can be regularly injected into the bearing. As the running speed of the bearing in this part is extremely low, the theoretical service life of the bearing can reach more than 15 years.

At the beginning of the research and development of this structure, it was considered to fix the head sheave ?shaft without rotation, and only allow all wheels to rotate relative to the shaft. Rolling bearings are used between each wheel body hole and the head sheave ?shaft to complete the above movement. The utility model has the advantages that the main bearings at the fulcrums at both ends of the head sheave ?shaft are saved, and the manufacturing cost is greatly reduced; The disadvantage is that this operation mode requires that the outer ring of the bearing at the inner hole of each wheel is at the same speed as the hoist while the inner ring is stationary, so there is a high requirement for the service life of the bearing. Because the selection of the bearing size is restricted by the head sheave ?shaft, the inner hole of the traveling wheel hub and the spacing of the head sheave ?wire rope, it cannot be more reasonable to select the bearing size according to the actual load and service life requirements, which makes the bearing service life lower and affects the service life of the entire head sheave ?device. Therefore, the structure shown in Figure 4 is safer and more reasonable.

In addition to meeting the strength and stiffness requirements in structure, the head sheave ?device shall be designed with emphasis on the characteristics of process and installation. During the design and manufacture of this structure, attention should be paid to the reasonable matching of the inner and outer rings of the rolling bearing with the head sheave ?shaft and the traveling hub. If the matching is not properly selected, it will cause incorrect installation or normal use.

3 Structure comparison

The design method and structure form of the head sheave ?device will have a great impact on its manufacturing process, and will also directly affect the manufacturing cost and use performance of the head sheave ?device. Table 1 analyzes and compares the head sheave ?devices with two structures, and points out their characteristics and shortcomings.