The structural characteristics and technical advantages of the elastic pin coupling

Published: 2018-07-26

Elastic pin couplingIt is a mechanical transmission device used to connect two shafts to rotate together to transmit torque and movement. It has a wide range of applications in various fields of the national economy.Since it is impossible to align the two connected shafts, the misalignment is caused by factors such as the manufacturing error of the unit, the installation error, the deformation after the load, and the temperature change.Therefore, the coupling is required not only to transmit torque and movement, but also to absorb the misalignment of the two shafts, and the additional impact on the unit should be as small as possible.The development and evolution of the coupling has always been carried out around this goal.

The elastic pin coupling relies on the elastic deformation of the elastic element to compensate the relative displacement of the two axes, and can also buffer and reduce vibration to avoid resonance.Elastic elements are divided into two types: metal elastic elements and non-metal elastic elements.Metal elastic element couplings include reed couplings, serpentine spring couplings, bellows couplings, diaphragm couplings and elastic pin couplings.Non-metal elastic element couplings still have many applications, including elastic pin couplings, rubber block couplings, and tire couplings.Compared with non-metallic elastic components, metal elastic components have greater load transfer capacity, no aging problems, long service life, and less influence on temperature. They are especially suitable for use in continuously operating industrial process power equipment.In particular, the emergence of the elastic pin coupling not only solves many problems existing in other early couplings, but also can easily adjust the design to meet the matching with the unit.Therefore, the elastic pin coupling has become a replacement for gear couplings and non-metallic elastic element couplings. It is a widely used elastic pin coupling, and its superior performance has become a product of turbo-compressor units.In recent years, it has played an important role in the transformation of some old units.

Structural features of elastic pin coupling:

1. The outer edges of the flanges of the two half couplings and the inner edge of the outer sleeve are made into half-element-shaped grooves with the same radius, which are combined into a pin hole to embed the pin.The half coupling of the driving shaft drives the outer sleeve through the pin, and the outer sleeve drives the half coupling of the driven shaft to rotate through the pin to transmit torque.The transmission torque is large. At the same torque, the rotation diameter is mostly smaller than the gear coupling, the volume is small, and the weight is lighter. It can partially replace the gear coupling.

2. Compared with the gear coupling, the structure is simple, the component parts are less, the manufacturing is more convenient, and the gear processing machine tool is not needed.

3. Working temperature -20~+70℃

4. The nylon pin is a self-lubricating material and does not need lubrication, which not only saves lubricating oil but also purifies the working environment.

5. Not suitable for noise requirements. Strictly control the parts to reduce the vibration energy and the noise.

6. You can use the expansion sleeve (locking plate) to connect.

7. Convenient maintenance and long service life. The nylon pin can be replaced by removing the baffle.

8. The shaft hole and keyway type and size of the coupling, and the marking method conforms to the requirements of GB/T3852-1997 "Coupling shaft hole and coupling type and size".

Technical advantages of elastic pin coupling:

1. Dry coupling, no need for lubrication

The elastic pin coupling relies on a metal diaphragm to transmit torque and absorb deformation caused by misalignment. There is no relative movement between parts, no friction and wear, so it does not need lubrication, which is in line with the development direction of oil-free process equipment.The gear coupling is a rigid movable coupling. It relies on the relative slippage between the tooth surfaces to compensate for the misalignment of the two shafts. Therefore, the gear coupling should be lubricated, and the lubrication condition determines the gear coupling The key to good or bad work.Especially when running at high speed, it appears to be prominent, such as the separation and leakage of oil under the action of centrifugal force, as well as the selection of lubricating oil, often because the lubrication design uses the bearing lubricating oil of the connected machine, rather than the appropriate load capacity Gear lubricants.Therefore, the lubrication problem of high-speed gear couplings is particularly prominent.On the other hand, the wear caused by the relative slippage of the tooth surface will cause a series of problems such as sludge and imbalance.Therefore, although gear couplings were once the choice for high-speed and high-power applications, with the emergence and development of elastic pin couplings, gear couplings have gradually faded out.

2. All-metal structure, large torque transmission capacity and long service life

The elastic pin coupling uses a metal diaphragm as an elastic element, which has a large load transfer capacity, and there are no non-metal parts in the whole product, no aging problem, long service life, and it is suitable for harsh use environments.This is a non-metallic elastic element coupling.

3. Great ability to compensate for misalignment and easy installation and alignment

The elastic pin coupling adopts austenitic stainless steel diaphragm, which can withstand large deformation while transmitting torsion, thereby compensating for the misalignment of the two shafts.The non-metal elastic pin coupling is restricted by the low strength and easy aging of the non-metal elastic element, which not only has a short life, but also has a small compensation ability.Gear couplings are restricted by the relative slip speed of the tooth surface and lubrication conditions. According to the information, the relative slip speed of the tooth surface should not be greater than 0.12m/s. The angular compensation ability is small.Therefore, non-metal elastic pin couplings and gear couplings require higher installation and alignment.Once the misalignment exceeds the allowable range, it will cause the coupling to fail.

4. Low axial and angular rigidity and little impact on equipment

The elastic pin coupling uses a thin metal diaphragm as the elastic element, and the angular and axial rigidity is low, so the additional axial force and additional bending moment are very small.Because the tooth surface of the coupling can slide relatively, people often think that the gear coupling can compensate for large angular and axial misalignment without additional impact on the unit.In fact, this idea is wrong.After the elastic pin coupling is loaded, due to friction and misalignment of the two shafts, a large additional axial force and additional bending moment will be generated on the shaft and the bearing.