Precautions for the installation of diaphragm couplings and the selection of couplings

The 8 points to pay attention to when installing the diaphragm coupling are as follows:

XNUMX. The allowable axis deviation of the coupling includes radial, angular and axial deviations.When installing, please adjust the axis deviation within the allowable value range of the corresponding product catalog.

XNUMX. When multiple deviations appear at the same time, the corresponding allowable value should be halved.

1. In order to prolong the service life of the coupling, it is recommended to set the axis deviation within 3/XNUMX of the allowable value.

XNUMX. Tighten the screws after inserting the mounting shaft, otherwise the coupling will be deformed.When tightening the screws, please use a torque wrench, do not use screws other than the accessories for installation.

XNUMX. If an abnormal sound occurs during operation, please stop the operation immediately and check the installation accuracy and screw loosening.It is recommended to apply adhesive on the outer surface of the screw after installation and debugging to increase the protection performance.

XNUMX. Products with diaphragms have edges and may cause injuries. It is recommended to wear thick gloves when installing.

XNUMX. Please install a protective cover and other devices around the coupling to ensure stability.

XNUMX. When the shaft center deviation exceeds the allowable value during installation, the coupling may be deformed, resulting in damage or shortened service life.

Diaphragm coupling (also known as lamination, steel sheet coupling) is a new type of two-axis coupling device that can replace gear couplings with general development prospects. It consists of two shafts at both ends and a diaphragm group. , Intermediate shaft and connecting bolts.Among them, the diaphragm group is formed by stacking some number of thin stainless steel coated diaphragms, through which torque and movement are transmitted.

Due to manufacturing and installation errors, load-bearing deformation, thermal deformation, and sinking of the base, the two shafts connected by the coupling will have a certain degree of relative deviation between the axes in the axial, angular, and radial directions. The displacement will cause additional load on the shaft, bearing and coupling, so that the diaphragm coupling can absorb the three-way offset between the axes through the flexibility of the diaphragm and improve the working conditions of the diaphragm coupling. It transmits large torque, and has the advantages of simple structure, convenient processing, and no need for lubrication, so it is widely used in aviation, shipbuilding, petrochemical industry, machinery manufacturing and other fields.

The diaphragm is the key element of the diaphragm flexible coupling. Due to the offset between the axes, the transmission of torque, and the bearing of centrifugal force, the diaphragm is in a complex state of stress during operation.Diaphragm deformation is a thin plate bending problem. In general, the pre-deformation of the diaphragm is small deformation, which is dealt with by the theory of small deflection.

The bolts of two adjacent holes on the diaphragm are respectively connected with the convex edges of the shafts at both ends and the intermediate shaft, that is, the bolts are arranged in opposite directions, resulting in a relative position between them through the flexibility of the diaphragm. When a hole is located When the position of is fixed, the normal force is caused by pre-deformation at the two adjacent holes, and the third hole that is separated by one hole can be fixed and restrained.

Choose the coupling you need:

XNUMX. Diaphragm couplings are particularly delicate and can be easily damaged if they are misused or not installed correctly during use.Therefore, it is particularly necessary to determine that the deviation is within the tolerance range of the normal operation of the coupling.

3852. Adjust the model according to the shaft diameter: The initially selected coupling size of the bearing coupling, that is, the shaft hole diameter d and the shaft hole length L, should meet the requirements of the shaft diameter of the driving and driven ends, otherwise it must be adjusted according to the shaft diameter d The specifications of the coupling.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 specified in GBTXNUMX should be selected. The shaft hole type is recommended to improve versatility and interchangeability. The length of the shaft hole is in accordance with the i-bearing coupling product standard.

XNUMX. The diaphragm coupling is composed of at least one diaphragm and two shaft sleeves.The diaphragm is fastened to the sleeve with a pin and generally will not loosen or cause backlash between the diaphragm and the sleeve.Some manufacturers provide two diaphragms, and some provide three diaphragms, with one or two rigid elements in the middle, and the two sides are connected to the shaft sleeve.

Fourth, the characteristic of diaphragm coupling is a bit like a bellows coupling. In fact, the way the coupling transmits torque is similar.The diaphragm itself is very thin, so it is easy to bend when the relative displacement load is generated, so it can withstand up to 1.5 degrees of deviation, while generating a lower bearing load in the servo system.

XNUMX. Diaphragm couplings are often used in servo systems. Diaphragms have good torque rigidity, but are slightly inferior to bellows couplings.

The diaphragm coupling relies on the elastic deformation of the diaphragm to compensate for the relative displacement of the connected two shafts. The diaphragm is not affected by temperature and oil pollution, and has the characteristics of acid resistance, alkali resistance, and corrosion resistance. It is suitable for high temperature, high speed and corrosive medium conditions. Environmental shafting transmission is the main coupling promoted in my country.

XNUMX. Deformation of the half coupling.Improper use or installation may cause the deformation of the half coupling, which will cause an abnormal bending stress on the diaphragm when the bolt is installed.Different from the aforementioned additional stress caused by the axial deviation, the bending stress is asymmetric for the diaphragm, and it occurs at the deformed part. The size and deformation degree of the bending stress, the thickness of the diaphragm, the number of bolts, the bolt radius, etc. Related factors are related.The deformation of the semi-coupling can easily cause vibration, noise, and premature diaphragm cracking.

In the overhaul, there are too few checks on the deformation of the half coupling.According to the relevant manufacturer's data, the outer circle and end face of the diaphragm semi-coupling are generally ≤0.05mm, diameter ＞250mm or the limit of the taper hole fit ≤0.08mm.Therefore, it is recommended to determine the maintenance process and check the deformation of the half coupling during installation to ensure that the equipment is operating normally.

XNUMX. Other minor issues should also be noted: the coupling mounting bolts cannot be replaced by ordinary bolts.The mounting bolts should be tightened according to the required torque.The direction of bolt penetration cannot be reversed.If the diaphragm has pre-stretching or pre-compression requirements, change it to determine the starting position between the prime mover and the equipment, and then add or subtract the adjusting shim on the coupling as required.The coupling and the shaft are matched with a tapered hole, so it is necessary to check the contact rate of the inner hole.

XNUMX. Dynamic balance.With the increase of the machine speed, the inertial main shaft of any rotating part has an eccentricity between the axis of rotation and the unbalanced moment of inertia generated during operation will inevitably cause the vibration of the transmission shaft system, leading to the failure of the machine parts.There are parts that can be relatively displaced in the flexible coupling, the more likely it is to cause imbalance.Therefore, the diaphragm coupling itself in many high-speed equipment has been dynamically balanced, and the half coupling is installed on the shaft and then dynamically balanced to determine the dynamic balance of the system.

For the unit, when maintenance and technicians pay more attention, the installation of the coupling will generally be carried out according to the design requirements.But for high-speed pumps, it is easy for maintenance personnel not to overlook the problem of wheel balance.Relative to the mass of the high-speed pump rotor, the proportion of the wheel is not small, and it is easy to produce a large unbalanced force at a high speed.The input shaft of the high-speed pump has relatively complicated force, and the unbalanced force easily interferes with the normal force of the bearings and gears, causing equipment abnormalities.Therefore, it is recommended to install the diaphragm coupling in strict accordance with the design requirements to ensure that the equipment can operate normally.