Precautions for the selection of serpentine spring coupling and its compensation ability

The serpentine spring coupling (hereinafter referred to as the serpentine spring coupling) is an elastic coupling in which several groups of serpentine springs are wound between the teeth of the two coupling halves to transmit motion and power.The flanges of the two halves of the coupling are provided with teeth of a specific shape, and serpentine springs are embedded between the teeth.When working, the torque of the driving shaft is transmitted to the driven shaft through the mutual extrusion of the teeth and the spring.Because the serpentine spring is an elastic element, it greatly improves the torque transmission capacity of the serpentine spring coupling, and has good compensation ability in the axial, radial and angular directions, so it is widely used in general mechanical occasions.

The spring force of the snake spring coupling, a simple stress analysis of the snake spring coupling, provides a basis for the development of the snake spring coupling product.However, there are still some shortcomings in these analyses. First of all, there is no specific analysis of the teeth on the half coupling. Second, the application of the load is not accurate enough during the stress analysis, and the results of the analysis will inevitably appear errors.As the main force-bearing component of the entire serpentine spring coupling, the half coupling is completed by the mutual extrusion of the spring and the teeth during the entire torque transmission process, so the toothed structure of the coupling is of great significance.

When the serpentine spring coupling is working, the torque of the driving shaft is transmitted to the driven shaft through the mutual extrusion of the teeth of the two halves of the coupling and the spring, thereby realizing motion transmission.The two halves of the coupling and the spring are the main stressed components of the snake spring coupling, and its material properties and structural shape are very important.

The tooth shapes on the two halves of the serpentine coupling are generally linear (diamond-shaped teeth) and curved (generally arc-shaped teeth).When the linear tooth works, the contact point between the spring and the tooth does not change with the change of torque, which is suitable for occasions where the torque does not change much; when the curved tooth works, the distance between the spring and the tooth contact point increases with the torque. Larger and smaller, suitable for occasions with large torque changes.The design of this paper selects curved teeth, and the cooperating serpentine spring bears the force.

Attention points for coupling selection and general steps:

　　1. Choose standard coupling

　　When choosing a coupling, the designer should first choose from the couplings that have been formulated as standards, mechanical industry standards, and obtained. Only when the existing standard couplings and couplings cannot meet the design needs, do they need to design the coupling by themselves. Shaft.

　　2. Select the type and type of coupling

　　Understand the comprehensive functions of the coupling (especially the flexible coupling) in the transmission system, and choose the type and type of the coupling from the overall design of the transmission system.According to the prime mover category and working load category, working speed, transmission accuracy, two-axis offset conditions, temperature, humidity, working environment and other comprehensive factors to select the type of coupling.Select the structure of the coupling according to the needs of the supporting host. When the coupling is used in conjunction with the brake, the coupling with brake wheel or brake disc should be selected; when overload protection is required, the coupling should be selected; When connecting with flanges, the flange type should be selected; for long-distance transmission, when the axial size of the connection is large, the intermediate shaft type or the intermediate sleeve type should be selected.

　　3. Calculation of coupling torque

　　The power of the power machine in the transmission system should be greater than the power required by the work machine.According to the power and speed of the power machine, the theoretical short moment T of the high-speed end connected to the power machine can be calculated; according to the working condition coefficient K and other related coefficients, the calculated torque Tc of the coupling can be calculated.The coupling T is inversely proportional to n, so the low-speed end T is greater than the high-speed end T.

　　4. Primary selection of coupling model

　　According to the calculated torque Tc, an approximate nominal torque Tn can be selected from the standard series, and the selection should satisfy Tn≥Tc.The coupling model (specification) is preliminarily selected, and the allowable speed of the coupling [n] and the larger radial dimension D and axial dimension L0 can be found from the standard, and the coupling speed n≤[n ].

　　5. Adjust the model according to the shaft diameter

　　The initially selected coupling size, that is, the shaft hole diameter d and the shaft hole length L, should meet the requirements of the main and driven end shaft diameters, otherwise the coupling specifications must be adjusted according to the shaft diameter d.It is a common phenomenon that the shaft diameters of the driving and driven ends are different. When the torque and speed are the same, and the shaft diameters of the driving and driven ends are different, the coupling model should be selected according to the larger shaft diameter.In the newly designed transmission system, the seven shaft hole types in accordance with GB/T3852 should be selected, and the J1 shaft hole type is recommended to improve versatility and interchangeability. The shaft hole length is in accordance with the coupling product standard. .

　　6. Choose the connection type

　　The choice of coupling connection type depends on the connection type of the main and driven ends to the shaft. Generally, a key connection is adopted, which is a unified key connection type and code. There are seven keyway types and four keyless connections specified in GB/T3852. , The most used is the A-type key.

　　7. Select the type, type and specification (model) of the coupling

　　According to the comprehensive factors such as power machine and coupling load category, speed, working environment, etc., select the type of coupling; select the coupling type according to the matching of the coupling and connection conditions; according to the nominal torque and shaft hole diameter Select the specification (model) with the length of the shaft hole.In order to ensure the strength of the shaft and key, after selecting the coupling model (specification), the strength of the shaft and key should be checked to determine the coupling model later.