How to connect the synchronous wheel and the shaft? Fixing method of synchronizing wheel and shaft
bondThe key connection is used to fix the pulley to the shaft, which is the most used connection method for materials such as steel and cast iron. However, when using the key connection for the aluminum alloy pulley, care should be taken not to cause the torque transmitted by the belt to affect the belt. The stress on the wheel keyway and the key contact surface exceeds the allowable stress of the aluminum alloy material.
1) The effect of key connection
The key connection is to complete the axial fixation between the shaft and the parts on the shaft through the key to transmit motion and torque. Among them, some types can also complete axial fixation and transfer axial force, and some types can complete axial dynamic coupling.
In the key connection device, the key (usually made of 45# steel) is a mechanical part used to connect the parts on the shaft and fix them in the circumferential direction to transmit torque. The connection types include looser bond connections, general bond connections and tighter bond connections.
2) The key to the device process of key connection
(1) Before installation, check the straightness of the key, the symmetry and parallelism of the keyway to the axis line.
(2) Generally, there is a gap between the two sides of the flat key and the shaft keyway. For heavy load, impact, and two-way use, there must be interference. The arcs at both ends of the key should have no interference. There should be a gap of 0.10mm between the key end and the shaft groove.
(3) Generally, the bottom surface of the flat key and the bottom surface of the keyway should be firmly attached.
(4) The radius of the semicircular key should be slightly smaller than the radius of the shaft groove, and other requirements are the same as the general flat key.
3) Use of key connection
The key is used to connect the shaft and the parts on the shaft, and it is fixed in the circumferential direction to transmit torque, such as the connection of Gears, pulleys, couplings and the shaft. The key connection can be divided into three types: loose key connection, tight key connection and spline connection. Category
Expansion sleeve connection
When the small gap between the key and the keyway has an impact on the use and requires the transmission equipment to have a high positioning accuracy or the same phase, the pulley and the shaft are mostly connected by a shrink sleeve. When using this connection method, the standard of the expansion sleeve should be selected according to the torque transmitted by the belt and the pressure on the surface of the expansion connection should be calculated.
1) The use of expansion sleeves makes the production and installation of host parts simple. The machining of the shaft and hole of the device expansion sleeve does not require high-precision production like the interference cooperation. There is no need for heating, cooling or pressurizing equipment when expanding the sleeve, only the bolts need to be tightened according to the required torque. And the adjustment is convenient, and the wheel hub can be conveniently adjusted to the desired orientation on the shaft. Sleeves can also be used to join poorly weldable parts.
2) The expansion sleeve has a long service life and high strength. The expansion sleeve relies on the conflict transmission, and there is no keyway weakening or relative movement of the jointed parts, and no wear occurs during work.
3) When the expansion sleeve is overloaded, the joint effect will be lost, which can protect the equipment from damage. The expansion sleeve combination can accept multiple loads, and its structure can be made into various styles. According to the size of the device load, multiple expansion sleeves can also be used in series.
4) The expansion sleeve is easy to disassemble and has excellent interchangeability. Because the expansion sleeve can combine the hubs with larger cooperation gaps, the bolts can be loosened when disassembling, so that the combined parts can be easily disassembled. When it is tightened, the touch surface is tightly attached and does not corrode, and it is also easy to disassemble.
Taper Sleeve Fastening
The hub and the bushing are connected by taper surface and fastened with bolts, and the bushing is connected with the shaft by keys.
In this way, three coupling holes can be seen on the coupling end face of the pulley, the bushing and the shaft. Two of them are device holes, which consist of half a threaded hole on the hub and half a light hole on the bushing. The other is the lead-out hole for disassembling the synchronous pulley, which consists of half a smooth hole on the hub and half a threaded hole on the bushing.
The thread length of the connecting bolt is slightly longer than the depth of the smooth hole. After the bolt is fully screwed into the smooth hole, and then continue to tighten the bolt, the bolt will pull the pulley and the bushing to fit tightly, and generate enough conflict force to transmit torque. . The bushing of this structure has a narrow groove in the axial direction, and the inner diameter of the bushing is also designed to be slightly smaller than the shaft diameter.
When installing, the small deformation of the narrow groove of the bushing can be used to install the pulley more simply. At the same time, after the bushing and the hub are connected, the inner hole deformation caused by the narrow groove will cause a small change in the inner diameter of the bushing, so that there is a certain amount of interference between the bushing and the shaft to ensure accurate torque transmission.
Other connection methods
Small-scale pulleys and resin pulleys and shafts with small transmission loads can be connected and positioned by means of D-shaped shafts, pins, set screws and elastic retaining rings.
