The characteristics of the scope of application of plum couplings and installation skills

Published: 2018-08-16

Plum couplingIt is a kind of elastic coupling. It is widely used in the transfer field of pulverized coal machine. It is widely loved by customers, such as large dosage, simple and cheap use.Plum-shaped elastic coupling: The working principle is to install a whole plum-shaped elastic ring between the two convex claws of the same shape half coupling to realize the connection of the two half couplings.The materials are mainly cast steel and 45# steel; the connection forms include keyway connection, set screw connection, clamping connection, or a combination of two forms of connection.

There are two main types of plum blossom couplings, one is the traditional straight claw type, and the other is the curved (concave) claw type zero-backlash coupling.The traditional straight-jaw plum blossom coupling is not suitable for use in high-precision servo transmission applications.The zero-backlash claw type plum blossom coupling evolved on the basis of the straight claw type, but the difference is that its design can be adapted to the application of the servo system, and is often used to connect servo motors, stepping motors and ball screws.The curved surface is to reduce the deformation of the elastic plum spacer and limit the influence of centripetal force on it during high-speed operation.The zero-clearance claw coupling is composed of two metal sleeves (usually made of aluminum alloy, stainless steel can also be provided) and a plum blossom elastic spacer.

The plum blossom elastic spacer has multiple leaf branches. Like a slider coupling, it also squeezes the plum blossom elastic spacer and the sleeves on both sides to match, and thus its zero clearance performance.Different from the slider coupling, the plum blossom coupling is driven by squeezing while the slider coupling is driven by shear.When using a zero-clearance claw coupling, the user should pay attention not to exceed the large bearing capacity of the elastic element given by the manufacturer (under the premise of zero clearance), otherwise the plum elastic spacer will be squashed and deformed and lose its elasticity. The disappearance of the preload, resulting in the loss of zero-gap performance, may also be discovered by the user after a serious problem occurs.

The plum coupling has a good balance performance and is suitable for high-speed applications (speed up to 30000 rpm), but it cannot handle large deviations, especially axial deviations.Larger eccentricity and deflection angle will produce a larger bearing load than other servo couplings.Another value of concern is the failure of the plum blossom coupling.Once the quincunx elastic spacer is damaged or fails, the torque transmission will not be interrupted, and the metal claws of the two shaft sleeves mesh together to continue to transmit the torque, which is likely to cause problems in the system.It is a big advantage of this coupling to choose the appropriate plum elastic spacer material according to the actual application.

The scope of application and performance characteristics of plum coupling

1. The plum blossom coupling is mainly composed of two protruding teeth that are closely meshed and subjected to radial compression to transmit torque. When the two axes are relatively offset, the elastic element undergoes corresponding elastic deformation, which plays a role of automatic compensation.

2.梅花联轴器主要适用于起动频繁、正反转、中高速、中等扭矩和要求高性的工作场合，例如：冶金、矿山、石油、化工、起重、运输、轻工、纺织、水泵、风机等。工作环境温度-35℃～+80℃，传递公称扭矩25～12500Nm，许用转速1500～15300r/min。

3. Compared with other couplings, plum couplings have the following characteristics:

(1) Stable work, with good damping, buffering and electrical insulation properties.

(2) The structure is simple, the radial dimension is small, the weight is light, and the moment of inertia is small, which is suitable for medium and high speed occasions.

(3) It has large axial, radial and angular compensation capabilities.

(4) Polyurethane elastic elements are resistant to oil, have large carrying capacity, and have a long service life.

(5) The coupling does not need lubrication, the maintenance workload is small, and it can run continuously for a long time.

The use of plum couplings is more and more widespread, but in many occasions the details of the installation of plum couplings are not very clear, resulting in a high rate of damage to the plum coupling and a lot of economic losses.The following are the installation tips of the plum blossom coupling.

(1) Before installation, check whether the two shafts of the prime mover and the working machine are concentric, whether there are wrapping paper and scratches on the surfaces of the two shafts, whether there are debris in the inner holes of the two half couplings of the plum coupling, and the edges of the inner holes Whether there are bruises; if any, the shaft and half coupling should be cleaned up, and the bruises should be treated with a fine file.Then check whether the inner hole diameter and length of the two half couplings are consistent with the diameter and shaft elongation of the prime mover and working machine.In general selection, it is better to let the length of the prime mover and the working machine end half coupling be less than the shaft extension of 2-2mm.

(2) In order to facilitate the installation, the two half couplings are placed in a 2-120 incubator or oil tank for preheating, so that the inner hole size is enlarged and it is easy to install.After installation, the shaft head should not protrude from the section of the half coupling, and it is better to be flush.Detect the distance between the two halves of the coupling:

Measure the readings of 3~4 points along the two inner sides of the flange of the half coupling and take the average value, and the sum of the measured dimensions of the extension section and the two diaphragm sets. The error of the two should be controlled within 0~0.4mm.

(3)找正：用百分表检测两半联轴节法兰盘断面和外圆跳动，当法兰盘外圆小于250mm时跳动值应不大于0.O5mm；当法兰盘外圆大于250mm时，跳动值应不大于0.08mm。

(4) Install the bolts: insert the bolts from the outside of the small hole of the flange, pass through the outside of the large hole of the other flange, put on the buffer sleeve and elastic washer, screw on the nut, and tighten the nut with a wrench.If the installation is unsuitable or if it is removed and replaced, it will not damage the shaft and the half coupling; after installation, it is better to rotate freely without holding back.

The installation of the coupling may cause accidents due to improper operations.

1. The axis of the coupling is skewed and the coupling will not advance: In order to prevent such accidents, in addition to correcting the axis, the position of the coupling hole and the shaft, and the position of the striker, attention should also be paid , The location of the impact point should be selected, one or two strokes should be light, and only after entering a certain distance (about 1/3), you can slam with force.

2. Other accidents may include: the impact block pulley moves backwards due to the unfastened position, the hoist chain slips off, the fuel is insufficient, the fire alarm, etc., all should be paid attention to in advance, and carefully checked during the tool preparation and operation training phase.

3. When the bearing, mechanical seal and other components have been installed on the main shaft in advance, it is forbidden to hit or hit the coupling forcefully to prevent damage or damage to the components.