In practical application, the coupling can be divided into heavy, medium, small and light according to the transmitted torque.

Heavy universal coupling is commonly used in metallurgical machinery, heavy machinery, petroleum machinery, engineering machinery, lifting machinery.

Medium and light universal couplings are commonly used in automobiles, machine tools and other vehicles and light industrial machinery.

Small universal couplings are mainly used to transmit motion and are generally used in precision machinery and control mechanisms. So how to choose the right coupling and what are the precautions when using it?

1 Application selection of coupling

1. Due to manufacturing, installation, load deformation and temperature changes and other reasons, when the installation adjustment, it is difficult to maintain the two axis strictly accurate.

There is some degree of X, Y direction displacement and skew angle CI. When the radial displacement is large, the slider coupling can be selected, and the universal coupling can be selected for the connection of large angular displacement or intersecting two shafts. When the two shafts produce a large additional relative displacement during the work process, the flexible coupling should be selected.

2. The working speed of the coupling and the size of the centrifugal force caused.

For high-speed drive shafts, couplings with high balance accuracy, such as diaphragm couplings, should be selected, and eccentric slider couplings should not be selected.

3. The size and nature of the torque required to be transmitted and the requirements for the damping function.

For example, for high-power heavy-duty transmission, gear couplings can be used; for severe impact loads or transmissions requiring the elimination of torsional vibration of the shafting system, tire couplings and other highly elastic couplings can be used.

4. The working speed of the coupling and the size of the centrifugal force caused.

For high-speed drive shafts, couplings with high balance accuracy, such as diaphragm couplings, should be selected, and eccentric slider couplings should not be selected.

5. The size and direction of the relative displacement of the two axes.

When the installation is adjusted, it is difficult to keep the two shafts strictly and accurately aligned, or the two shafts will produce a large additional relative displacement during the work process, the flexible coupling should be used. For example, when the radial displacement is large, the slider coupling can be selected, and the universal coupling can be used for the connection of large angular displacement or intersecting two shafts.

6. Coupling reliability and working environment.

Usually, non-lubricated couplings made of metal components are relatively reliable; the performance of couplings that need lubrication is easily affected by the degree of lubrication and may pollute the environment. The coupling containing non-metallic components such as rubber is sensitive to temperature, corrosive medium and strong light, and is easy to age.

7. Manufacture, installation, maintenance and cost of couplings.

Under the premise of meeting the convenient performance, the coupling with convenient assembly and disassembly, simple maintenance and low cost should be selected. For example, the rigid coupling is not only simple in structure, but also easy to assemble and disassemble, and can be used for low-speed, rigid transmission shafts. General non-metallic elastic element couplings (such as elastic sleeve pin couplings, elastic pin couplings, plum-shaped elastic couplings, etc.) are widely used in general medium and small power transmission due to their good comprehensive ability.

2 matters needing attention in the use of coupling

01, coupling is not allowed to have more than the specified axis line skew and radial displacement, so as not to affect its transmission performance.

02. After the universal coupling is installed, it will run normally for one shift. All fastening screws must be checked. If looseness is found, it must be tightened again with the specified tightening torque. This will be repeated for several shifts to ensure that it will not loosen.

03, universal coupling sliding surface, crosshead, bearing, etc. must ensure lubrication, generally use 2# industrial lithium-based grease or 2# molybdenum disulfide calcium-based grease, under normal conditions, continuous operation 500 hours refueling once, intermittent operation 2 months refueling once a week, if working under high temperature conditions must be refueling once a week, refueling the bearing end face oil hole screw unscrew, with a high pressure oil gun to inject until overflow.

04. During daily maintenance of the coupling, if normal wear phenomena such as indentation are found, it should be replaced in time; the coupling is not allowed to have cracks, and if there are cracks, it needs to be replaced (you can use a small hammer to knock and judge according to the sound); During maintenance and disassembly, the cross shaft is rotated by 180 ° to achieve alternating use of the journal under stress.

05, gear coupling tooth width contact length shall not be less than 70%; The axial movement shall not be greater than 5mm.

06. The tooth thickness of the gear coupling is worn. When the lifting mechanism exceeds 15% of the original tooth thickness, when the operating mechanism exceeds 25%, it should be scrapped, and when there is a broken tooth, it should also be scrapped.

07. The elastic ring of the pin coupling and the sealing ring of the gear coupling should be replaced in time if they are damaged and aged.

08, in the work operation, should always observe whether the universal coupling abnormal radial swing and bearing heating and other phenomena, found that these phenomena must be timely maintenance.

Source: mechanical equipment maintenance