General concepts

Belt pulley is a kind of disc hub part, and its manufacturing process is generally casting and forging. Generally, the larger size is designed by casting method, and the material is generally cast iron, rarely cast steel; Generally, the smaller size can be designed for forging, and the material is steel. The belt pulley is mainly used for long-distance transmission of power, such as tractors, automobiles, mining machinery, machining equipment, lathe air compressors, reducers, reducers, generators, gin, etc.

The selection of various indicators and materials of the pulley is based on the principle of minimizing raw materials, making the process feasible and minimizing the cost on the premise of meeting the use requirements.

Advantages and disadvantages of belt drive

Advantages:

1. The belt pulley transmits energy to mitigate load impact;

2. The belt pulley drives stably, with low noise and vibration; The structure of belt pulley drive is simple and easy to adjust;

3. The manufacturing and installation accuracy of pulley drive is not as strict as that of meshing drive;

4. The belt pulley drive has the function of overload protection;

5. The adjustment range of the center distance between the two shafts of the belt pulley drive is large.

Disadvantages:

1. The belt pulley transmission has elastic sliding and slipping, and the transmission efficiency is low and the accurate transmission ratio cannot be maintained;

2. When the belt pulley transmission transmits the same circumferential force, the profile size and shaft pressure are larger than those of the meshing transmission;

3. The pulley drive belt has a short life.

Belt pulley specification

The diameter and other dimensions of the pulley of various mechanical equipment are matched according to the reduction ratio, and designed according to the working speed and motor speed. Working speed/motor speed=driving wheel diameter/driven wheel diameter * 0.98 (slip coefficient). If steel pulley is used, the linear speed is required to be no higher than 40m/s; if cast iron is used, the linear speed is required to be no higher than 35m/s.

The pulley must be made into various grooves according to the shape of the V-belt; These different grooves determine various types of belt pulley, such as O-type pulley, A-type pulley, B-type pulley, C-type pulley, D-type pulley and E-type pulley.

The national standard specifies seven types of V-belts, namely, O, A, B, C, D, E, F, and three corresponding pulley groove angles, namely, 34 °, 36 °, and 38 °. At the same time, it specifies the minimum diameter of small pulley corresponding to each pulley groove angle for each type of V-belt, but not for large pulley. The groove angle of the belt pulley is divided into 32 degrees, 34 degrees, 36 degrees and 38 degrees. The specific selection shall be based on the groove type and reference diameter of the belt pulley;

install

1. Check the pulley groove to ensure that there is no scar or sharp edge, and all dimensions meet the standard;

2. Clean all component surfaces, such as hub holes, taper sleeves, bolt holes, etc. Fit the cone into the pulley so that all screw holes are aligned.

3. Apply oil on the screw and thread and screw them into the mounting hole, but do not tighten them temporarily.

4. Clean the surface of the transmission shaft, push the pulley with taper sleeve installed to the predetermined position on the shaft, and check whether the triangular pulley is aligned.

5. When using the keyway, it must be inserted into the hub first, and there must be a certain tolerance between the keyway and the hub.

6. Tighten the bolts of each mounting hole gradually and evenly alternately until the required torque is reached.

7. After a short period of operation (0.5 to 1 hour), check the tightening torque of the bolts and retighten if necessary.

8. In order to prevent foreign matters from invading, fill the connecting hole of the hole with grease.

disassemble

1. Loosen all bolts, take out one or two bolts according to the number of removal holes, and insert the bolts into the removal holes.

2. Tighten the bolts alternately until the taper sleeve and pulley are loosened.

3. Take out the taper sleeve and belt pulley from the shaft.

Precautions for assembly

1. Before assembly, it shall be cleaned to ensure that the mating surface fits closely without oil stain and has sufficient friction.

2. The hexagonal socket bolts used for assembly shall also be cleaned before assembly to ensure that the bolts have sufficient friction self-locking capacity after fastening.

3. The hexagon socket bolts shall be tightened alternately to ensure that the taper sleeve is subjected to uniform axial force and the belt pulley and taper sleeve are well aligned.

4. After the pulley is fastened, check and adjust the relative positions of the driving and driven pulleys to ensure that the two pulleys are on the same plane.

6. The pulley cover shall be intact and firmly installed.

7. The cone sleeve is a vulnerable part. After a long time of operation, the inner hole and chain slot may be damaged. Before each assembly, check it and replace it in time if any defect is found.