1. Role of guide
The guide is a device to prevent the deflection of the lift car and counterweight when they move up and down to ensure the smooth operation of the elevator. The guides are installed on the car and counterweight device, and the car guides are installed on the top beam of the car and the bottom of the car. A total of four sets of counterweight guides are installed on the top and bottom of the counterweight frame. During operation, the concave groove (or roller) of the guide is matched with the convex working surface of the guide rail, so that the car and counterweight device only move up and down along the working surface of the guide rail to prevent the car and counterweight device from deflecting or swinging during operation.
2. guide classification and structure (elevator guide system --- guide)
The guide can be divided into sliding guide and roller guide according to the different movement modes between the guide and the working surface of the guide rail. The sliding guide can be divided into fixed sliding guide and elastic sliding guide according to whether the axial position of the shoe head is adjustable. The fixed sliding guide (see Figure 1 for appearance) is mainly composed of shoe liner and shoe base, which is also called rigid sliding guide. Due to the large gap between the shoe liner of the fixed guide and the top surface and two sides of the guide rail at the shoe head position, it usually produces large vibration and impact during movement, so it is usually used for elevators with less than 1m/s requirements for operation quality. Because of its simple structure, high rigidity and strong bearing capacity, it is widely used in low-speed and large-tonnage freight elevators.
The elastic sliding guide is composed of shoe base, shoe head, shoe lining, shoe shaft, compression spring or rubber spring adjusting sleeve or adjusting nut, and is also divided into one-way floating spring type and rubber spring type sliding guide. The one-way floating spring-type sliding guide can play a buffering role in the direction perpendicular to the top surface of the guide rail, but there is still a large gap between it and the working surface of the guide rail side, which makes it have no buffering effect on the vibration and impact of the working surface on both sides of the guide rail. Therefore, the upper limit of the rated speed of the elevator using this structural guide is generally 1.75m/s rubber spring-type elastic sliding guide because the shoe head has certain directionality, Therefore, the buffering performance on the working faces on both sides of the guide rail has also been improved, and the applicable elevator speed range has also increased accordingly.
The roller guide, also known as roller guide, is composed of roller, spring and rocker arm of shoe seat. Since the roller guide uses rolling contact, it can reduce the friction resistance between the guide and guide rail, and reduce vibration and noise. It is often used in high-speed elevators.
3. Main factors affecting guide friction
The friction between elevator guide and guide rail is a dynamic and complex process coupled with many factors, which will be affected by many factors such as shoe lining material, lubrication state, relative speed of contact load and surface roughness.
(1) Shoe lining material. The shoe lining material of sliding guide is generally wear-resistant nylon hard plastic, glass fiber cast iron or other polymer materials. Zhang Xingang et al. studied the influence of nylon shoe liner and rigid plastic shoe liner on friction coefficient under the same working condition through experiments. Ni Ting also compared the friction properties of nylon glass fiber reinforced polytetrafluoroethylene and ultra-high molecular weight polyethylene under four sliding conditions in his paper. By comparing the data under different materials, we can know that different shoe lining materials have different friction characteristics.
(2) Lubrication status. Under the condition of lubrication, a layer of oil film will be formed between the guide rail and the shoe liner to separate the shoe liner and the guide rail, and the dry friction will be converted into wet friction, which greatly reduces the friction coefficient and reduces the friction. Generally speaking, the friction force under lubrication is much smaller than that under dry friction. Therefore, the sliding guides should generally be lubricated to reduce friction.
(3) Contact pressure. The contact pressure between the guide and the guide rail surface mainly comes from the balance reaction force generated by the offset of the lift car load. The normal pressure on the guide can sometimes reach more than 1000. Different materials have different sensitivity to contact load. Generally speaking, the friction coefficient will decrease with the increase of normal pressure. Although the friction coefficient decreases, the whole friction increases with the increase of pressure.
(4) Operating speed. Under a certain pressure, the wear will increase with the increase of the speed, reach a certain maximum, and then decrease with the increase of the sliding speed.
(5) Surface roughness. Under the same load conditions, the rougher the surface, the greater the friction force, the more serious the wear. There is a most reasonable surface roughness under each load. At this time, the minimum wear exceeds this roughness and the wear will rise again. This is because the surface roughness is too small to increase the contact area, and the intermolecular attraction enhances the lubricant can not be stored in the friction surface, which is easy to cause adhesion and friction bite.
4. Routine maintenance of guide
The guide is an important device to keep the elevator running smoothly. Whether the guide works normally will directly affect the elevator noise comfort? Smoothness and leveling error, etc. Therefore, daily maintenance of guides should be done well.
The elevator is a special equipment. According to Item 10 of the half-month maintenance items and requirements of the Safety Technical Code for Special Equipment (TSG/T5001-2009) "Rules for the Use, Management and Maintenance of Elevators", the basic requirement for the maintenance of the oil cup on the guide is to check that the oil absorbent felt is complete, the oil quantity is appropriate, and the oil cup is free of leakage. Quarterly maintenance items and requirements? The basic requirement is that the amount of clean wear shall not exceed the requirements of the manufacturer. As a professional elevator maintenance personnel, it is not enough to only meet these basic maintenance requirements. A responsible enterprise should strictly control all links from the purchase of parts and components, the installation of elevator to the subsequent maintenance and maintenance, ensure the strength, hardness, wear resistance and other mechanical properties of the boot lining material, ensure the processing quality of the working surface of the elevator guide rail, ensure the straightness of the guide rail during the installation of the elevator, and the parallelism of the two guide rails to the plumb line to ensure the spacing and rigidity of the guide rail mounting bracket and the gap repair at the guide rail joint. The maintenance and inspection of the sliding guide after the elevator is put into operation should start from the following aspects.
(1) The clearance between the side of the shoe liner of the car guide and the guide rail is 0.5~1mm. The adjustment range of the guide spring with no clearance between the shoe liner of the elastic sliding guide and the top surface of the guide rail does not exceed the standard. The clearance between the fixed sliding guide liner and the top surface of the guide rail is 1-2mm. The clearance between the counterweight guide liner and the top surface of the guide rail is not more than 2.5mm.
(2) Check the upper guide and counterweight guide of the lift car. People stand at the top of the car, run the car and counterweight maintenance at the horizontal position suitable for inspection, swing the car or counterweight frame back and forth to check the size of side clearance and top clearance and the wear of shoe lining, and also check the spring force of the spring. Check the guide at the bottom of the car: the maintenance personnel should stand in the pit and move the car to the lowest suitable maintenance position, and check the condition of the guide by shaking the car back and forth. If the top clearance is too large, remove the shoe liner and add shims on its top surface for adjustment. If the side clearance is too large, the side clearance can be adjusted by adjusting the bolts of the side shoe liner. The integral shoe liner can be adjusted by adding shims on the back of the shoe liner side to make the gap slightly larger on the side. If the effect is not ideal after adjustment, the best way is to replace the new boot lining.
(3) Keep the guide rail clean and lubricated, and timely remove and clean the dirt on the guide rail surface and inside the shoe liner. Because the up and down movement of the lift car will drive the air flow and the dust flying in the shaft. These sand and dust are easily adsorbed on the working surface of the guide rail, causing serious wear of the boot and guide rail. Therefore, the working surface of the guide rail of the sliding guide should be cleaned as required to ensure the normal operation of the guide, reduce the friction noise during operation, and improve the service life of the shoe liner.
(4) The shoe liner is seriously worn and jammed with foreign matters, the gap is too large or the installation is skewed, which will cause the rail gnawing phenomenon when the car is running. When carrying out routine maintenance, it is found that there are narrow and bright scratches on the side of the guide rail. In serious cases, the side of the shoe liner with burr is worn unevenly and has burr. When the car is starting and leveling, it is found that the car deviates, twisting and other phenomena can basically be judged that the rail gnawing occurs. There are many reasons for rail gnawing, which are mainly caused by the installation of the guide rail being twisted and skewed or loose, and the installation of the upper and lower guides being not aligned, and the gap between the guide rail and the car frame being deformed or the shoe seat bolt being loose, and the overall dimension of the shoe liner being too small, shaking in the shoe head. At this time, adjust and eliminate rail gnawing and replace shoe liner according to specific reasons.
5. Conclusion
Whether the shoe liner of sliding guide is iron, nylon or hard plastic, there is always friction between the shoe liner and the guide rail during the elevator operation. This friction not only increases the load of the tractor, but also is one of the reasons for the vibration and noise of the lift car during operation. In order to reduce the friction between the guide and the guide rail, save energy, improve ride comfort, enhance the daily inspection and maintenance, cleaning, lubrication, adjustment and timely replacement of the guide liner, the roller guide can be replaced if necessary.
More about EPEN Multi-layer Sliding Bearings：
Jiashan Epen Bearing Co., Ltd. is a professional manufacturer of sliding bearings, metal plastic composite bearings business, specializing in adhering to do fine, the better for our customers continue to create value concept, is committed Sliding Bearings, new composite materials research, development, promotion and applications. Company's existing main products for metal-plastic composite series Sliding Bearings, bimetal bearings, sliding bearings single metal series, are widely used in automotive, metallurgy, engineering machinery, construction machinery, plastics machinery, machine tool industry, water conservancy and hydropower 30 a number of areas.
Epen Multi-layer Sliding Bearings include EU Bushing, EX Bushing, EU PTFE lined Steel base Bearing, EU PTFE lined Stainless Steel base Bearing, EUB PTFE lined Copper base Bearing, EX POM lined Steel base Bearing, EV PVDF lined Steel base Bearing, EV PVDF lined Copper base Bearing, EK PEEK lined Steel base Bearing, EXB POM lined Copper base Bearing.
For example, EU tri-layer maintanence-free bushing have a base of lower carbon steel, onto which a porous bronze layer is sintered. PTFE mixtures are impregnated into the intersice of this bronze layer after rolling process completed. Eu has good physical & mechanical properties, also has certainly chemical properties. It is suitable for rotary, oscillating movement with performance of self-lub. Anti-wear, lower firction, lower noise.
