1. Raising questions

1.1 due to the influence of geological conditions, there are many inclined shafts and lanes in each production mine of tieneng company, and the chairlift is mainly used for auxiliary transportation personnel. Because the chairlift operates economically, there are many transportation personnel, and it can be transported continuously for a long time, with high safety and reliability. It has been widely used in tieneng company. There are 8 production mines in the headquarters of tieneng company, and 10 sets of chairlifts are used. Due to the large use of chairlifts in tieneng company, safe operation is very important.

1.2 from 2000 when the first set of overhead man riding device of tieneng company was put into use, to 2010, all mines have been using right alternating twist fine wire rope as the rope for overhead man riding device according to the manufacturer's recommendation. However, in the process of use, it is found that the steel wire rope is easy to break, the service life is short, the replacement is frequent, and the joint is easy to loose in use. Most of them have to add a section of steel wire rope after running for a period of time, resulting in a waste of economy and manpower and hidden dangers to safety production.

1.3 the steel wire rope of the chairlift is a closed annular rope formed by the head wheel and tail wheel. The operation mode of the steel wire rope is shown in Figure 1:

2. Cause analysis

2.1 in order to solve the above problems, we consulted a large number of materials, consulted relevant manufacturers and conducted on-site investigation. It was found that there were many misunderstandings in the selection of steel wire rope for chairlift, such as considering that the cross twisted fine wire steel wire rope has good flexibility and is not easy to rotate and loose strands. It is applicable to the use of chairlifts. However, this is not the case in actual use. Although the fine wire has good flexibility, it is not wear-resistant, and it is easy to break the wire. Although the interactive twist is not easy to rotate, the flexibility is not good, and it is also easy to break the wire. Although the interactive twist steel wire rope itself is not easy to loose, in the actual plug-in, the joint is good at the beginning, but the joint becomes more and more loose after running for a period of time. Through consultation with relevant manufacturers, field investigation and consulting a large number of data, it is found that the right common wire rope with the same direction can solve the above problems well in practical use. After consulting the data, it is found that the interactive twist steel wire rope has the following characteristics: this kind of steel wire rope has the disadvantages of large rigidity and short service life. The utility model has the advantages that it is not easy to loosen and twist, and is widely used in hoisting machinery. The same twist wire rope has the following characteristics: good contact between wire ropes, smooth surface, good flexibility, small wear and long service life, but it tends to rotate and loose easily. Therefore, it should not be used in the crane with free hanging heavy objects. It is usually used as a traction rope and should not be used as a lifting rope.

2.2 through analysis and summary, it is found that under the same service conditions, the chairlift selects the right common steel wire rope with the same direction than the right interactive fine wire rope. In addition to being easy to rotate, it has a long service life, is not easy to break the wire, and the joint is not easy to loose. The advantages far outweigh the disadvantages.

3 Application Comparison

3.1 after summary and analysis, it is decided to test and use the right common wire rope in the same direction on the chairlift of Daming mine with large slope (20 degrees), long haul distance (800 meters) and the largest number of people. The overhead man riding device in Daming mine was installed in 2000. From the beginning of installation, the right alternating twist fine wire rope (6 strands of 37 wires, with a rope diameter of ① 26mm) has been used according to the manufacturer's recommendation. However, there are many problems in the process of use, such as easy wire breakage and short service time. During the use, due to the loose joint, the joint section had to be cut off and a section of steel wire rope was added before re plugging. Due to the frequent replacement of steel wire rope, it not only caused economic losses, but also brought hidden dangers to safety production. This problem has been perplexing relevant technicians. Through communication, Daming mine agreed to try it out.

3.2 comparative analysis on the use of right alternating twist filament steel wire rope in Daming mine, the shortest and longest use time are selected, as shown in Table 1

Through the investigation, the steel wire rope of the chairlift in Daming mine was replaced quite frequently before, with a minimum of two and a half months and a maximum of five months, with an average service time of four months. Moreover, the joint must be cut off once or twice during the service period, and the rope must be inserted.

3.3 situation of Daming mine using right common wire rope with same direction twist Daming mine replaced the steel wire rope of chairlift with right common wire rope with same direction twist (6 strands and 19 wires) on May 31, 2010. After installation, it has been used until February 19, 2011, for a total of 7.5 months. See Table 2 for comparison of rope inspection records.

Through comparative analysis, the right common wire rope with the same twist direction has the characteristics of slower wire breaking speed and longer service cycle than the interactive fine wire rope. In addition, the connector is not loose in use, and there is no need to cut off the connector and plug it again.

4. Special treatment of joint during insertion. While changing the type of steel wire rope, the mine has also taken certain measures for joint insertion. During insertion, according to the provisions of coal mine safety regulations, the insertion length is 1000 times the diameter of steel wire rope and should not be less than 26m, but in the actual insertion, the technicians extended the length to 50m. The plug strength of the connector is improved. In the process of inserting, the hemp rope core 10 meters in the middle of the joint is retained, and the iron rope core 20 meters at both ends (using a strand of steel rope as the iron rope core) is wrapped with insulating tape for two layers to improve the friction coefficient, so as to prevent joint tap and loose strand. The effect is good, and there is no additional steel rope in use. 5 solution to the problem of steel wire rope rotation during installation. In the installation process, the steel wire rope is easy to rotate whether it is alternately twisted or in the same direction, especially in the same direction. The rotation of the steel wire rope of the chairlift can cause a large swing range of the passenger chair, especially at the head and tail, the swing can cause the scraping machine base. Therefore, it is particularly important to eliminate the rotation of steel wire rope. Preventive and remedial measures are taken in the actual installation. During the rope laying process of installation, the crane is used to suspend the rope bundle, so that the rope bundle rotates with the rope out, so that the paved steel wire rope is not "stiff", and the rotation caused by the steel wire rope itself during installation is prevented. See Figure 2:

If the rotation of the steel wire rope is obvious after installation, the following remedial measures can be taken: remove the hanging chair, double the counterweight iron of the tail wheel and idle for 24 hours. If there is still rotation, idle for 72 hours to eliminate the rotation.

6 economic benefit and safety benefit analysis through comparison: the economic benefit and safety benefit are greatly improved by using the right common wire rope with the same direction twist and the right interactive fine wire rope. Taking Daming mine as an example, 90000 yuan can be saved annually. Due to the reduction of replacement times, the potential safety hazards in the process of replacement construction are reduced. Special treatment is carried out for the joint, which reduces the risk of loose strands of the joint and brings benefits to safety production.

7 conclusion by comparing the data before and after using the right alternating twist fine wire rope and the right common wire rope in the same direction in the chairlift under Daming mine, and analyzing the economic benefits, it is concluded that the right common wire rope is not easy to break, has good flexibility, the joint is not easy to loose, and has a long service life. Popularizing the use of right common wire rope in the same direction on the chairlift of tieneng company can increase the service life of the wire rope, reduce the hazards such as broken wire and loose joint, and improve the economic and safety benefits.