Created on:2021-08-17 14:37

Maintenance of hydraulic prop_ Solution to seal failure of hydraulic cylinder

液压支柱的维修_液压缸密封失效的解决
Maintenance of hydraulic prop_ Solution to seal failure of hydraulic cylinder

    单体液压支柱是广泛用于高档普采工作面的支护设备,其可靠性与寿命直接影响煤矿井下工作面的支护质量与安全高效生产。某矿区各矿在籍的单体液压支柱有近10万根,每年需要大修的支柱达3万多根,每年需新增加支柱和报废支柱基本保持在1万根左右,单体液压支柱实际使用平均寿命很难达到5a。每年都要在大修上投入大量资金,但修复后的单体支柱质量并不令人满意,各大修单位技术重点应该放到何处,是非常值得关心和亟待解决的问题。
Single hydraulic prop is widely used in high-grade common mining face support equipment, its reliability and life directly affect the quality of coal mine underground working face support and safe and efficient production. There are nearly 100000 single hydraulic props in each mine of a mining area. More than 30000 props need to be overhauled every year. The number of new props and abandoned props need to be increased every year is about 10000. The actual average service life of single hydraulic props is difficult to reach 5 years. A large amount of money is invested in the overhaul every year, but the quality of the repaired single pillar is not satisfactory. It is a very important and urgent problem to be solved where the technical focus of each overhaul unit should be.

(1)液压缸修复方案的选择
(1) The choice of repairing scheme for hydraulic cylinder

通过对单体液压支柱多年大修的数据分析和调查,发现导致支柱密封失效的位置一般出现在活柱一活塞、顶盖一液压缸等处的密封配合上,而主要故障点集中发生在液压缸一活柱间(见图V),支柱工作性能的可靠性很大程度取决于该密封点的工作能力。
Through the data analysis and investigation of the overhaul of single hydraulic prop for many years, it is found that the sealing failure position of the prop generally occurs in the sealing fit of the piston, the top cover and the hydraulic cylinder, and the main failure point mainly occurs between the hydraulic cylinder and the movable column (see Fig. V). The reliability of the working performance of the prop largely depends on the working capacity of the sealing point.

V.jpg

    作为单体液压支柱的一个非常容易受损的部件,缸体内腔以锈蚀泄漏为主,同时工作状态和搬运时的磨损、磕碰也会使得内腔尺寸增大、缸体变形,从而导致密封失效,因而对其修复方法的合理选择具有特别的意义。
As a very easy damaged part of the single hydraulic prop, the inner cavity of the cylinder is mainly corroded and leaked. At the same time, the wear and collision in the working state and transportation will also increase the size of the inner cavity and deform the cylinder, resulting in the failure of the seal. Therefore, the reasonable selection of the repair method has special significance.

    ①液压缸内壁镶不锈钢套工艺 由于不锈钢具有很强的防腐能力,代替液压缸易于腐蚀的内表面,大大增强了支柱的抗腐蚀能力,提高了支柱的使用寿命。该工艺采用先将φ100孔的内径在原部位去掉一定厚度材料后镶入不锈钢套,经旋压而完成定径,再用机加工恢复其内径尺寸和粗糙度等级。不锈钢套为定型产品,有壁厚0.8mm与0.6mm两种,根据使用经验,可选用规格为壁厚0.8mm的钢套,镗φ100孔时镗刀头的尺寸调整为101-0.45-0.48,镗完内孔后将不锈钢套嵌入缸体,多余不锈钢材料割除。旋压是最后一道工序,实际上是通过旋压头上的滚柱对不锈钢套表面进行挤压,使缸套产生塑性变形,从而使钢套紧紧地贴在缸体内壁上。旋压是通过压力使不锈钢套延展变形、阻力变大,完成后的尺寸公差和内腔表面粗糙度应分别达到100+0.060和Ra3.2μm。采用该工艺修复液压缸后,支柱的大修维修期延长60%以上,同时质量稳定可靠。
① The technology of inlaying stainless steel sleeve in the inner wall of hydraulic cylinder, because stainless steel has strong anti-corrosion ability, can replace the easily corroded inner surface of hydraulic cylinder, greatly enhance the anti-corrosion ability of the prop, and improve the service life of the prop. In this process, the first φ After removing a certain thickness of material from the original part, the inner diameter of 100 holes is inserted into a stainless steel sleeve, and the diameter is determined by spinning, and then the inner diameter and roughness grade are restored by machining. The stainless steel sleeve is a set product with wall thickness of 0.8mm and 0.6mm. According to the use experience, the steel sleeve with wall thickness of 0.8mm can be selected for boring φ When the hole is 100, the size of the boring head is adjusted to 101-0.45-0.48. After boring the inner hole, the stainless steel sleeve is inserted into the cylinder block, and the excess stainless steel material is cut off. Spinning is the last working procedure. In fact, the roller on the spinning head extrudes the surface of the stainless steel sleeve to produce plastic deformation of the cylinder liner, so that the steel sleeve is tightly attached to the inner wall of the cylinder block. Spinning is to make the stainless steel sleeve extend and deform and increase the resistance by pressure. The dimension tolerance and surface roughness of inner cavity should reach 100 + 0.060 and ra3.2 respectively after spinning μ m。 After using this technology to repair the hydraulic cylinder, the overhaul period of the prop is extended by more than 60%, and the quality is stable and reliable.

    ②液压缸热喷涂修复工艺ZD-1粉末涂料是一种非金属材料,具有优良的防腐耐磨性能,将它加热后,喷涂在液压缸内孔表面上作为防腐层,能彻底消除电镀金属层带来的阳极腐蚀。待修液压缸通过冷挤扩径、整形、热喷涂ZD-1粉末涂料、珩磨、检验多道工序后,即可出厂。
② ZD-1 powder coating is a kind of non-metallic material with excellent anti-corrosion and wear resistance. After heating, it can be sprayed on the surface of the inner hole of the hydraulic cylinder as an anti-corrosion layer, which can completely eliminate the anodic corrosion caused by electroplated metal layer. After cold extrusion, shaping, thermal spraying ZD-1 powder coating, honing and inspection, the hydraulic cylinder to be repaired can leave the factory.

    本工艺克服了镗削扩孔的繁杂工序,减少了机加工量,也避免了缸壁减薄问题,并由于液压缸在“冷挤扩径”过程中始终处于拉应力状态,因而兼有“冷挤硬化”效应,减少了弯曲变形,提高了液压缸强度。
This technology overcomes the complicated process of boring and reaming, reduces the amount of machining, and avoids the problem of cylinder wall thinning. Because the hydraulic cylinder is always in the state of tensile stress in the process of "cold extrusion expanding", it has the effect of "cold extrusion hardening", reduces the bending deformation and improves the strength of the hydraulic cylinder.

(2)密封方式选用方案
(2) Selection of sealing method

    通常液压缸一活柱之间采用Y形。在支柱工作时,乳化液由三用阀注入缸体内部,活柱与液压缸相对运动,由于液压缸简体径向位移量的作用,其动密封点(Y形密封圈处)始终处于密封松弛状态,支柱内腔压力越高,液压缸简体的径向位移量越大,密封点密封越松弛,同时,密封泄漏的可能性越大。在顶板快速来压,附加较大冲击载荷时,使得液压缸内腔压力瞬时增高20%以上,液压缸简体径向位移量相应加大,液压缸简体内表面与Y形密封圈的密封更加松弛,造成密封泄漏。大修中,可使用具有自动补偿功能的密封圈,对于内径胀大超差、表面粗糙度下降1~2级、缸体内壁麻坑直径小于2mm或表面涂层脱落等缺陷的液压缸均能,达到良好的密封效果。其具体工作原理是通过将高压乳化液引入密封圈内部,随着支柱内腔压力的升高,密封圈与液压缸的接触面增大,从而在液压缸磨损处实现密封补偿,加强了密封效果。采用密封补偿和密封胀紧的方式,有效减少了Y形密封圈处的泄漏,减少了密封更换率及维修次数,具有良好的经济效益和社会效益。
Generally, Y-shape is used between the hydraulic cylinder and the movable column. When the prop is working, the emulsion is injected into the cylinder by the three-way valve, and the movable column moves relative to the hydraulic cylinder. Due to the radial displacement of the hydraulic cylinder, the dynamic sealing point (at the Y-shaped sealing ring) is always in a state of sealing relaxation. The higher the pressure in the inner cavity of the prop, the greater the radial displacement of the hydraulic cylinder, and the looser the sealing point is. At the same time, the greater the possibility of sealing leakage is. When the roof is pressed rapidly and a large impact load is added, the pressure in the inner cavity of the hydraulic cylinder increases by more than 20% instantaneously, the radial displacement of the cylinder increases correspondingly, and the seal between the inner surface of the cylinder and the Y-ring becomes more loose, resulting in seal leakage. During overhaul, the sealing ring with automatic compensation function can be used to achieve good sealing effect for the hydraulic cylinder with defects such as inner diameter expansion out of tolerance, surface roughness decreasing by 1-2 grades, pockmark diameter less than 2mm or surface coating falling off. The specific working principle is to introduce the high-pressure emulsion into the seal ring. With the increase of the pressure in the inner cavity of the prop, the contact surface between the seal ring and the hydraulic cylinder increases, so as to realize the sealing compensation at the worn part of the hydraulic cylinder and strengthen the sealing effect. By using the way of sealing compensation and sealing expansion, the leakage at the Y-shaped sealing ring is effectively reduced, and the sealing replacement rate and maintenance times are reduced, which has good economic and social benefits.

    该工艺方法在该矿区各矿及大修厂已推广使用,大大降低了液压缸——活柱之间密封的故障率。通过对新技术、新工艺在单体液压支柱大修中的应用,不仅提供了解决单体液压支柱的损坏率和报废率高问题的方法,也使得解决局部大修的技术难题成为可能。
The technology has been widely used in all mines and overhaul plants in the mining area, greatly reducing the failure rate of the seal between the hydraulic cylinder and the movable column. Through the application of new technology and new process in the overhaul of single hydraulic prop, it not only provides a method to solve the problem of high damage rate and scrap rate of single hydraulic prop, but also makes it possible to solve the technical problems of partial overhaul.
The technology has been widely used in all mines and overhaul plants in the mining area, greatly reducing the failure rate of the seal between the hydraulic cylinder and the movable column. Through the application of new technology and new process in the overhaul of single hydraulic prop, it not only provides a method to solve the problem of high damage rate and scrap rate of single hydraulic prop, but also makes it possible to solve the technical problems of partial overhaul.

Home    Article    Maintenance of hydraulic prop_ Solution to seal failure of hydraulic cylinder