Elevator traction wheel rope groove wear and improvement measures - Database & Sql Blog Articles

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Analysis of the causes of rope groove wear

Due to various reasons of design, manufacture, installation and traction system itself, after a period of operation of the elevator, the rope grooves on the traction sheave that are in contact with the hoisting rope produce different degrees of wear, with the degree of wear Increasingly, it has a certain impact on the safe operation and comfort of the elevator.

Let's take a case of an elevator installed and operated by a certain factory in a certain place as an example. After two years of use, the elevator often makes an abnormal sound during operation, accompanied by car shake, and the ride comfort is poor. After inspection, it was found that the tension of one of the six traction wire ropes changed greatly. When the car was running to the top layer, the wire rope was almost unstressed, and the weight of the car was completely absorbed by the other five wire ropes, but the car When the car is running down, the tension of the wire rope is getting larger and larger. When running to the middle landing, the tension of the six wire ropes is basically the same, but when the car is close to the bottom layer, the tension of the wire rope is obviously much exceeded. The remaining five, indicating that it bears the load of most cars. As a result, the rope head combination spring of the wire rope is subjected to intense compression and colliding with the rope head plate to make a "beep" sound, and causes a large jitter of the car. Since the wire rope is too loose or too tight during operation, it cannot be simply tightened or loosened. Through inspection, it was found that the rope grooves of the traction sheave have worn out and the degree is different. The rope groove where the wire rope with abnormal tension is located is particularly worn compared with the other 5 grooves. After measuring by the feeler gauge, the groove is worn more than 1.6 mm in the radial direction than the remaining five, which is obviously the main cause of the abnormality of the wire rope.

Taking the ladder as an example, it is known that the diameter of the traction sheave is D=650 mm, and the vertical lifting distance of the elevator is 30 m, and the tension of each wire rope is substantially the same in the intermediate layer, and the slip of the wire rope is not counted for the wire groove worn by 1.6 mm. The traction wheel rotates 1 revolution per revolution, and the wire rope moves 10.1 mm less than the other five. According to this calculation, when the intermediate layer of the six wire ropes whose running tension is substantially the same is 15 m up or down, the wire rope moves 74.2 mm less. Therefore, in order to compensate for this stroke, the wire rope generates a large elastic elongation when descending, and causes the car to have a certain degree of inclination through the rope head plate. Since the wire rope is subjected to an alternating load in a large range, it is easy to break, resulting in a decrease in the safety factor, and at the same time, the car is tilted and shaken during operation, so that the ride comfort is greatly reduced.

According to the actual situation, the traction sheave is removed in time, and the rope grooves are reworked according to the corresponding size, so that the pitch diameter is consistent within the allowable error, and the tension of each traction wire rope is adjusted. After a period of trial The running elevator returned to normal.

The following analysis of the causes of the degree of wear of the rope groove of the traction sheave is different. The wear of the rope groove of the traction sheave is caused by the slip between the traction rope and the rope groove of the traction sheave, and the greater the slip amount, the greater the degree of wear.

The total slip amount S should consist of two parts:

1 The slip amount S1 caused by the elastic tensile strain of the traction rope, assuming that the tension of the rope on both sides of the traction sheave is T1 and T2, where T1>T2, when the elevator is running, the elastic elongation of the steel rope on the T1 side increases. Large, when turned to the T2 side, since T1>T2, the elastic elongation decreases, causing the wire rope to slip in the groove, and the direction is toward the side with the large tension, causing the rope to creep in the groove. This is one of the main reasons for the continuous wear of wire ropes and traction rope grooves. Obviously, it is assumed that the hardness of each rope groove of the traction sheave is the same. When the tensions T1 and T2 on both sides of the traction rope are substantially the same, the wear amount of each rope groove of the traction sheave should be basically the same, but it is likely to be installed in the elevator. During commissioning, the tension T' of a certain wire rope exceeds the allowable error compared with the rest of the wire rope tension, that is, T"1/T"2 > T1/T2, the creeping distance of the rope in the groove is correspondingly increased. This causes the rope groove to wear more severely than the remaining 5 slots.

2 Sliding rope caused by the pressure of the rope groove S2: The safe operation of the traction type elevator is that there is sufficient friction between the traction sheave and the hoisting rope. The condition that the traction should meet is (T1/T2). ) C1 · C2 ≤ ef, where T1/T2 - the car carrying 125% of the rated load is located at the lowest landing and the empty car is at the highest landing, the larger static tension in the wire rope on both sides of the traction sheave The ratio of the smaller static tension. It is inferred from the downward trend of the no-load car with poor traction conditions. When the car suddenly stops at a deceleration, the tension difference on both sides of the traction sheave exceeds the anti-skid limit, causing the rope to slip in the groove. When the static tensile force ratio T1/T2 of a certain steel wire rope is larger than the other steel wire ropes, the slip of the steel wire rope is more serious; as the elevator frequently brakes, the rope groove wears to make the diameter smaller, the slippage is more serious, and the wear is also The more it gets worse. In general, when the traction wheel groove wear differs by more than 1/10 of the diameter of the hoisting rope, the traction sheave should be replaced or reworked.

In general, the wear of the traction sheave is caused by the relative slip of the traction rope in the rope groove. The greater the slippage, the more serious the wear; and the sliding of the traction rope relative to the rope groove Depending on the tension ratio of the hoisting ropes on both sides of the traction sheave, as the tension ratio of the hoisting rope in the rope groove increases, the slip amount also increases.

2 Improvement measures

1 This paper analyzes the assumption that the wear resistance and hardness of each rope groove of the traction sheave are the same. In fact, if the wear resistance, hardness and pitch diameter of each rope groove are inconsistent. It is obvious that the amount of wear caused is also inconsistent. Therefore, the performance indicators of the traction sheave should be strictly controlled within the scope of the national standard.

2 The tension of each hoisting rope should be adjusted so that the difference between them is within 5%.

3 When the elevator is running during the inspection and found that the rope groove is out of wear, the traction sheave must be replaced or reworked to adjust the tension of each wire rope to make it basically the same.

4 It is recommended to use a polyurethane rope groove gasket on the traction sheave. The gasket is embedded in the corresponding wheel groove, and the transverse groove is processed on the gasket. The friction coefficient of the suitable corrugated wheel facing the unlubricated steel rope is almost unchanged, and the polyurethane is particularly wear-resistant, which improves the life of the gasket. It also greatly increases the service life of the wire rope.