Rolling Drum

Rolling Drum

The reel is an important load-bearing part of the crane. It winds the wire rope through the action of the motor to realize the lowering or lifting of the lifting weight. It carries the lifting load, retracts the wire rope, and realizes the lifting of the pick-up device. Therefore, the safety and reliability of hoisting machinery reels are very important.

 

Rolling drum is the component to wind wire rope in the lifting mechanism. Rolling drum consists of drum shaft, flange type annular gear,drum hub, bearings, bearing pedestal.When one end of drum is equipped with the switch of rotary type position limitation limiter , it must ensure to make drum shaft and rising limit switch rotate synchronously.

 

Drum material generally adopts cast iron. For special use, drum can be welded with cast steel or steel plate.

 

 

(1) The type of roll.

 

According to the shape of the cylinder, it can be divided into long-axis reel and short-axis reel.

 

According to the manufacturing method, it can be divided into casting reel and welding reel.

 

According to whether there is rope groove on the surface of the reel, it can be divided into smooth surface and spiral groove surface reel.

 

According to the number of layers of wire rope wound on the drum, it can be divided into single-layer winding drum and multi-layer winding drum.

 

Generally, most cranes use single-layer winding drums, and multi-layer winding drums are used for cranes with extremely large lifting heights or requiring compact structures (such as truck cranes).

 

(2) The structure of the reel.

 

The reel is composed of a cylinder, a connecting plate, a shaft and a bearing bracket.

 

The surface of the cylinder of the single-layer winding reel is cut with a spiral groove with an arc-shaped section to increase the contact area between the steel wire rope and the cylinder, and to fix the winding position of the steel wire on the drum to avoid the influence of adjacent steel wires rubbing against each other. life.

 

The surface of the cylinder body of the multi-layer winding drum is usually smooth without spiral grooves, and there are flanges at both ends of the cylinder body to prevent the steel wire rope from slipping out.

 

The disadvantage is that the steel wire ropes are closely arranged, and each layer overlaps and rubs against each other, which has a great impact on the life of the steel wire rope.

 

Among the structural dimensions of the drum, the key dimension that affects the life of the wire rope is the calculated diameter of the drum.

 

 

2. Fixing of the wire rope on the drum

 

Usually, pressure plate screws or wedges are used to fix the tail of the wire rope by using the principle of friction. The fixing method is required to be safe and reliable, easy to check and assemble, and not to cause excessive bending or damage to the wire rope at the fixing point.

 

(1) Wedge fixation method.

 

This method is often used for steel wire ropes with smaller diameters, does not require bolts, and is suitable for multi-layer winding drums.

 

(2) Long slat fixing method.

 

Through the pressing force of the screw, the long strip with groove is fixed on the drum along the axial direction of the wire rope.

 

(3) Press plate fixing method.

 

Fixing the wire rope with a pressure plate and screws is the most common form of fixing, which is simple, reliable, and convenient for observation and inspection. Its disadvantage is that it takes up a lot of space, so it cannot be used for multi-layer winding. Considering safety, the number of pressing plates should be at least 2.

 

In order to ensure the reliable fixing of the wire rope tail and reduce the stress on the pressure plate or wedge, when the pick-up device is lowered to the lower limit position, 1.5 to 3 safety rings should be reserved on the reel in addition to the wire rope fixed ring. It is called a load shedding ring, which has been considered in the design of the reel.

 

In use, the more the number of turns of the wire rope tail is retained, the smaller the force on the pressure plate or wedge of the rope tail, and the safer it will be. If the lower limit position of the pick-up device is too low in the case of hoisting, and the remaining number of wire ropes on the drum is less than the designed number of safety turns, it will be caused by the force on the end of the wire rope exceeding the pressing force of the pressure plate or wedge. The wire rope was pulled off and the heavy object fell.

 

 

3. Reel safe use requirements

 

(1) The fixing device at the end of the wire rope on the drum should have the performance of anti-loosening or self-tightening. The fixing condition of the end of the wire rope should be checked once a month. In any state of use, it must be ensured that the wire rope retains enough safety rings on the drum.

 

(2) The end of the cylinder of the single-layer winding reel should have a flange. The flange should be 2 times the diameter of the wire rope or the width of the chain higher than the outermost wire rope or chain.

 

The reel should be scrapped when one of the following conditions occurs:

 

① crack;

 

② The wear amount of the cylinder wall reaches 20% of the original wall thickness;

 

③ When the wear of the rope groove is greater than 1/4 of the diameter of the wire rope and cannot be repaired.

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