Fixing method of star coupling and using damage factors

Published: 2018-07-05

The star coupling is made of engineering plastics as an elastic element. It is suitable for connecting two coaxial transmission shafts. It has compensation for the relative deviation of the two shafts, cushioning, shock absorption, and energy. It is suitable for general occasions and transmits torque 20-35000 .NM, working temperature -35-+80 degrees Celsius and interchangeable with German ROTEX coupling.The polyurethane elastomer of the star coupling is limited by the convex claw block, which can avoid the internal deformation caused by impact and the external deformation caused by the centrifugal force; the polyurethane plastic of the star coupling is the elastic element, which has cushioning and shock absorption. ,, convenient disassembly and assembly, etc., the working temperature is -35~+80 degrees.The polyurethane elastomer is limited by the convex claw block, which can avoid the internal deformation caused by impact and the external deformation caused by centrifugal force; the large concave surface of the convex claw makes the surface pressure on the involute tooth very small, even if the tooth is overloaded , The teeth will not wear or deform.

The radial movement of the star coupling due to centrifugal force during high-speed operation will accelerate its wear, and a shell is added.In addition to the star coupling can prevent dust and oil storage, insufficient thinning may cause interference. Excessive thinning will weaken the strength of the tooth, and the backlash will be large.The contact condition of the external teeth avoids the disadvantages of squeezing the edge of the straight tooth and stress concentration under the condition of angular displacement. At the same time, the friction and wear of the tooth surface are reduced, the noise is reduced, and the maintenance cycle is long.The tooth end of the outer gear sleeve of the star-shaped elastic coupling is in the shape of a horn, so it is not suitable for use under high speed and impact load conditions, nor for the connection of vertical shafts.When designing the overall structure of the star coupling, pay full attention to the lubrication and dust prevention between the tooth surface and the roller, as well as the protective effect.Because if the chain breaks, it may cause a personal accident.The radius of curvature of the bulge curve is proportional to the single-sided thinning of the internal teeth, that is, it is related to the meshing gap of the teeth, which makes the assembly and disassembly of the internal and external teeth easy.

The correct choice of star coupling

1. The performance and working environment of the star coupling.Star couplings usually made of metal elements that do not require lubrication are better; star couplings that require lubrication are easily affected by the degree of lubrication and may pollute the environment.Star couplings containing non-metallic components such as rubber are more sensitive to temperature, corrosive media and strong light, and are prone to aging.

2. The size and nature of the torque to be transmitted and the requirements for the buffer and vibration reduction function.For example, for high-power and heavy-duty transmissions, toothed star couplings can be used; for transmissions that require severe impact loads or shaft torsional vibrations, tire-type star couplings and other highly elastic star couplings can be used. Shaft.

3. The magnitude and direction of the relative displacement of the two axes.When it is difficult to keep the two shafts in strict alignment after installation and adjustment, or when the two shafts will have a large additional relative displacement during the working process, a flexible star coupling should be used.

4. The manufacture, installation, maintenance and cost of star couplings.Under the premise of meeting the convenience of performance, a star coupling that is convenient for assembly and disassembly, simple maintenance, and low cost should be selected.

5. The working speed of the star coupling and the centrifugal force caused by it.For high-speed transmission shafts, star couplings with high balance accuracy, such as diaphragm star couplings, should be used, and eccentric slider star couplings should not be used.

Fixing method of star coupling

1. Locating screw fixation: The two locating screws have a gap of 90º to lock the fixed shaft. In the traditional fixing method, because the front end of the screw contacts the shaft, it may cause damage to the shaft or difficulty in disassembly.

2. Clamping screw fixation: Utilize the tightening force of the hexagon socket bolt to shrink the slit and clamp the shaft tightly.This method is convenient to fix and disassemble, and will not cause damage to the shaft, so it is a very common fixing method.

3. Keyway type fixation: suitable for high-torque transmission. In order to prevent axial sliding, it is usually used together with positioning screws and clamping screws.

4. D-shaped hole fixation: Generally, if the motor shaft is D-shaped, if the positioning screw cannot be fixed, the hole of the star coupling can be processed into a D-shaped hole corresponding to the size of the motor shaft. With the positioning screw fixed, there is no need to worry about slipping.

5. Expansion sleeve fixation: tighten and fix the account cover by tightening the four positioning screws on the end face of the star coupling. It is suitable for the connection and fixation of some stepping motors and servo motors with large torque, such as the expansion sleeve diaphragm star. Type coupling, expansion sleeve plum blossom star coupling, expansion sleeve bellows star coupling, etc.

Installation of star coupling:

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

2. The characteristic of the star 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.

3. Star couplings are often used in servo systems. The diaphragm has good torque rigidity, but it is slightly inferior to bellows couplings.

4. On the other hand, the star coupling is very delicate, and it is easy to be damaged if it is misused or not installed correctly during use.Therefore, the deviation is very large within the tolerance range of the normal operation of the coupling.

5. 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 main and driven end shaft diameters, otherwise they must be adjusted according to the shaft diameter d The specifications of the coupling.

In addition to the quality problems and torsional vibration of the star coupling, the principle of the star coupling cannot be underestimated.

1. Principle: The main star coupling of the star coupling is a torsionally loaded rubber component. The rubber component can be designed in a single row or multiple rows. Each rubber component has a variety of standard stiffnesses to choose from, which can be used in a wide range. To meet the rigidity requirements determined by the torsional vibration calculation, the star coupling.The main purpose of using a highly elastic star coupling in a ship's power system is to transmit power and torque, compensate for radial, axial and angular alignment errors, and compensate for the oscillation of rotational momentum.Adjust the natural vibration frequency of the system.The star coupling has the characteristics of light weight, easy installation, large displacement compensation in all directions, large damping, vibration absorption capacity and frequency modulation, etc., which can better protect the main star coupling, gear box and shaft system.

2. Reason analysis: (1) The elastic shock absorber of the main engine sinks, causing the shafting to be misaligned, and additional torque is generated!This possibility is great for new ships. (2) Star coupling heating and breaking accident; (3) Matching problem: only the various equipment in the shafting, such as diesel star coupling, high elasticity pin star coupling, gear box, shafting Other parts, propellers, etc. are well designed and complement each other and support each other, and they all improve the design level, so that the designed ship is a ship in the sense.