What are the characteristics of the coupling?

Many people have heard of couplings, but don’t know what they are. According to understanding, couplings have many characteristics. So, what are the characteristics of couplings after all? The following is the content about it. Hope to make us have a harvest!

Characteristics of coupling

According to the structure, the coupling can be divided into two types: flexible coupling and rigid coupling, which can be treated separately according to its structure.

1. Flexible coupling

Flexible couplings are widely used couplings for CNC machine tools. They can compensate for the "dry and" phenomenon caused by errors in coaxiality and straightness.Under the condition that the structure allows, most of the servo feed systems of CNC machine tools use flexible coupling structure.However, it is difficult to know whether the taper sleeve is locked when the flexible coupling is installed. If the frictional force is insufficient after the taper sleeve is expanded, the relative slippage between the screw shaft head and the motor shaft head will change, resulting in the operation of the CNC machine tool. In the process, the dimensions of the processed parts show regular and gradual changes (from small to large or large to small), and the value of each change is basically stable.If the rapid feed rate of the machine tool is adjusted, this amount of change will also change. At this moment, the CNC system does not alarm, because the motor rolling is normal, and the encoder's response is also normal.Once the machine tool presents this situation, the method of simply tightening the two-end screws does not necessarily work.The solution is to try to lock the elastic tapered sleeve of the coupling. If the tapered sleeve is too loose, the tapered sleeve can be slit axially. After tightening the screws at both ends, the problem can be completely eliminated.

2. Rigid coupling

For rigid couplings, the coupling method of coupling sleeve and taper pin is the first choice, and most of the feed motor shafts are equipped with flat keys.This kind of connection, through a period of use, the taper pin becomes loose at the beginning, and the gap on the side of the keyway gradually increases, sometimes even causing the taper pin to fall, resulting in unstable parts processing dimensions.There are two ways to deal with it:

(1) Use a special small-head taper pin with a thread and lock it with a nut and an elastic washer to avoid loosening of the taper pin due to rapid conversion.This method can well deal with the problem of the looseness of the tapered pin, and at the same time, it also reduces the torque received by the flat key.Of course, in this way, because the small head of the tapered pin has a nut, it is necessary to ensure that the coupling has a certain reversal space.

(2) Choose two elastic pins, one large and one small, to replace the tapered pin. Although this method does not have the high accuracy of the tapered pin, it can handle the loosening of the tapered pin. The elastic pin has certain elasticity and can be used. The split part of the flat key accepts the torque, and the structure is compact, and the installation is also very convenient.After being used in repair, it works very well.But pay attention to when installing, the large and small elastic pins must be installed at 180° to each other, otherwise it will affect the accuracy of parts processing.

The feed organization of CNC machine tools uses servo motors or stepping motors to connect with ball screws. Generally, direct couplings, toothed synchronous belts, or gears are used.

Because the feed speed of CNC machine tools is relatively fast, such as fast forward and fast rewind, sometimes the speed is as high as 20m/min or more, and the forward and reverse reversals are frequently changed during the entire processing process.The momentary impact that the coupling receives is relatively large, which simply causes the coupling to loosen and change. As the time of use increases, the loosening and changing conditions aggravate.In practice processing, the first manifestation is that the movement in all directions is normal, the encoder response is normal, and the system has no alarm, but the movement value has not been able to match the command value, the processing error value is getting larger and larger, and the processed parts are even scrapped.When this situation occurs, it is recommended to check the coupling.

The feed organization of CNC machine tools uses servo motors or stepping motors to connect with ball screws. Generally, direct couplings, toothed synchronous belts, or gears are used.In many occasions, due to structural constraints, especially after the selection of a servo motor or a hybrid stepping motor, the direct coupling of the coupling has become the most common connection method between the motor and the ball screw.

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The content of the coupling was introduced above. After reading it, we should have a certain understanding of it. Interested friends can also learn more about other couplings we have collected.