Research on high pressure mechanical rotary seal w

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Research on medium diameter water medium high pressure mechanical rotary seal

[Abstract] this paper analyzes the structure and working principle of a new large diameter water medium high pressure mechanical rotary seal, and discusses the design and calculation method of the fracture elongation of the dynamic seal ring - the elongation when the sample breaks. The experimental research shows that the sealing theory is feasible, the structure is reasonable, the sealing gap has automatic compensation performance, long service life, small leakage, stable performance, and can meet the requirements of industrial application. Its sealing principle can be extended to the large and medium diameter seals of roadheader and other high-pressure rotary liquid supply systems, and has a good application prospect

Study on a High-pressure Water Mechanical Swivel for a Middle Diameter

Wang Jiangsheng et al

Abstract:For solving the problem of high-pressure water swivels for a larger diameter,a new type seal,high-pressure mechanical swivel with auto-controlling gap is developed, And its structure and working principle are is found th, but we should not consider too high and too low prices as much as possible. At the new swivel has many advantages of reas, the average riding frequency of each shared bicycle is more than 3 times. Onable structure, auto controlling gap, long service life, lower leak and greater durability et al, and can be use in the systems of supplying high-pressure fluid in road-header and other machines.

keywords:high pressure mechanical swing, high pressure water, water lubrication, auto controlling gap, middle diameter seal

1 preface

in recent years, high-pressure water jet technology has been more and more widely used in various fields, and the internal and external spray dust suppression system on mining machinery in the coal industry has increasingly shown its advantages. In order to supply water to the rotating heading head of the roadheader, the large-diameter high-pressure rotary seal is an essential key component. However, according to the field application results, the main factor affecting its normal operation is the poor high-pressure rotary sealing technology of the water supply system. In order to solve the problem of sealing life, the rh-25 cantilever roadheader developed by Anderson company in the UK adds a set of intermediate gear transmission device between the cutting head spindle and the cutting motor, providing a space for the small-diameter rotary sealing device. This structure has two shortcomings: first, the length of the machine has been increased by more than 1m; Second, the middle transmission device is biased and heavy, so the machine vibrates greatly during operation. The roadheader produced by British dosoc company also did not solve this problem well. Due to the short sealing life, which affects the normal operation of the machine, many coal mines have dumped the high-pressure water spray dust suppression system for this purpose

at present, the high-pressure rotary seals widely used in mining machinery at home and abroad are mostly packing seals or ring seals, such as O-rings, YX lip seals, l-seals, combined v-seals commonly used on high-pressure pumps, and high-pressure drum seals widely used in the hydraulic system of coal mine hydraulic supports. These seals have the following problems:

(1) the seals can rotate with the shaft, but cannot be fixed along the circumference, so they are suitable for reciprocating motion, Do not rotate

(2) the sealing material is rubber or nylon, which deforms seriously under high pressure, and the sealing gap is difficult to control. When moving at high speed, the heat is large and not easy to diffuse, which is very easy to burn the seal, so it is not suitable for long-term work under high-speed and high-pressure conditions

(3) the greater the seal pressure, the greater the seal rotation torque and the greater the energy consumption

the coal mine conditions are relatively bad. When the roadheader spray dedusting, the performance of the high-pressure mechanical rotary seal is required to be reliable, the service life is more than 1 year (the overhaul period is 1 year, about 1000 ~ 5000h), the maintenance is convenient, and the cost of the relevant test parameters of the input samples is low. In view of this situation, the current high-pressure rotary seal can not meet its requirements. From a new point of view, this paper studies the high-pressure mechanical rotary seal with automatic gap compensation

2 sealing structure and working principle

the general mechanical seal is to limit the leakage of working fluid medium along the rotating shaft. The seal studied in this paper is to send high-pressure working fluid from stationary parts to rotating parts

figures 1 and 2 show the structural diagram and component photos of the test seal. The test seal is a 60 ~ 80mm diameter non-equilibrium medium diameter high-pressure rotary seal with symmetrical structure. The main components are seal end cover (static seal ring), seal ring (dynamic seal ring), seal housing, rotating shaft, spring and bearing, etc

Figure 1 gap automatic compensation high pressure rotary seal structure

1 Shaft; 2. Bearing cover; 3. End cover; 4. Shell; 5. Sealing ring; 6. O-ring

7. Spring; 8. Anti rotation pin; 9. End cover fastening bolts; 10. Fastening bolts of bearing cover; 11. Bearing

Figure 2 photos of test sealing parts

the dynamic sealing ring rotates with the shaft and slides along the axial direction of the stop pin. The spring presses the two seal rings to both ends to keep the end faces of the dynamic and static seal rings in contact. In the seal, the O-ring acts as a static seal

high pressure liquid enters the seal from the hole in the middle of the seal housing and flows out of the core hole of the rotating shaft. After the high-pressure liquid enters the seal cavity, a hydraulic pressure pair is generated on both sides of the dynamic seal ring (as shown in Figure 3). The combined action of hydraulic pressure and spring force makes the dynamic seal ring compress on the seal end face, and the seal depends on the contact of both sides. The relative sliding between the two contact surfaces will cause wear. The material of the dynamic seal ring is soft and the wear is fast. After wear, the dynamic seal ring slides axially to always ensure that the seal clearance remains unchanged, which is the principle of automatic compensation of seal clearance. The pressure produced by the unbalanced sealing liquid on both sides of the dynamic sealing ring is unbalanced

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