The selection of Cardan shaft mainly considers the speed of the shaft to be transmitted, the size of the load, the installation accuracy of the two parts to be connected, the stability of rotation and the price, etc. The coupling type is selected according to the characteristics of various coupling.
About the selection of Cardan shaft:
1. Due to manufacturing, installation, load deformation and temperature change, it is difficult to keep the two shafts in strict and accurate alignment after installation adjustment. There are some displacement and skew angle CI in X and Y directions. When the radial displacement is large, the sliding coupling can be selected. The universal shaft can be used for the connection of the two axes with large angular displacement or intersection. When the two shafts produce large additional relative displacement during the working process, flexible coupling shall be selected.
2. The working speed of universal coupling and the centrifugal force caused. For high-speed transmission shaft, coupling with high balance precision, such as diaphragm coupling, should be selected, but it is not suitable to select the eccentric slider coupling.
3. The torque size and nature to be transmitted and the requirements for buffering vibration function. For example, for heavy-duty transmission with high power, gear coupling can be selected. For the transmission of severe impact load or requirement to eliminate torsional vibration of shaft system, tire coupling can be selected. Most of the couplings have been standardized or standardized. The designer’s task is to choose, not design.
The basic steps for selecting universal joint shafts are as follows:
According to the load transfer, the speed of the shaft, the installation accuracy of the two parts, a joint type is selected according to the characteristics of various universal coupling.
1. The torque size and nature to be transmitted and the requirements for the buffering and damping function are also required. For example, for heavy-duty transmission with high power, gear coupling can be selected; For the transmission with severe impact load or requirement to eliminate torsional vibration of the shaft system, the coupling with high elasticity such as tire coupling can be selected.
2. The magnitude and direction of the relative displacement of the two axes. When it is difficult to keep the two shafts accurately aligned after installation and adjustment, or when the two shafts will produce large additional relative displacement during the working process, flexible coupling shall be selected. For example, when the radial displacement is large, the sliding block coupling can be selected. The universal shaft can be used for the connection of the two axes with large angular displacement or intersection.
3. Reliability and working environment of Cardan shaft. Generally, the universal coupling made of metal elements without lubrication is reliable; The performance of coupling which needs lubrication is easily affected by the lubrication perfection and may pollute the environment. The coupling with non-metallic elements such as rubber is sensitive to temperature, corrosive medium and strong light, and is easy to aging.
4. Manufacture, installation, maintenance and cost of universal coupling. On the premise of satisfying the convenience performance, the coupling with convenient installation and disassembly, simple maintenance and low cost should be selected. For example, the rigid coupling is not only simple in structure, but also convenient for installation and disassembly, and can be used for low speed and large rigid transmission shaft. The general non-metallic elastic element coupling (such as elastic sleeve pin coupling, elastic column pin coupling, quincunx elastic coupling, etc.) is widely used in general medium and small power transmission due to its good comprehensive ability.
