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Tube Mill High Pressure Principle Of High And Low Pressure Oil Stations In Tube Mill
Jul 27, 2017

Tube Mill High Pressure Principle of High and Low Pressure Oil Stations in Tube Mill

According to the manufacturing diagram of the tile, the contact between the slip ring and the tile is within the range of 550mm × 550mm (Figure 3). According to this situation, the parameters such as pressure and flow are extremely complicated. Therefore, the contact range can be reduced to a circle of φ550 mm (as indicated by the dotted line in Fig. 3), and the calculation result is corrected. In addition, the radius of the tile (R2197mm) and φ550mm compared to the larger difference, according to the characteristics of the fluid, but also the static pressure film can be assumed in a plane gap; slip ring radius R2195mm, by calculating the edge of the contact , The gap between the slip ring and the tile is only 0.0157mm (Figure 8), and then consider the elastic deformation of the tile, and finally the hydrostatic film can be assumed in two circular parallel plane formed within the gap (Figure 9 ). Figure 9 in the small circle of the ds segment from the inside out of the flow can be considered parallel to the gap of the gap, the gap width of 2πs, the gap length ds, the gap is δ.

This has four gaps in the actual "high pressure" (14MPa ~ 20MPa) of the four tava. The result is that the thickness of the gap between the tent and the slip ring is constant, and the actual thickness of the oil film gap is gradually increasing from the inside to the outside (although small, but still present, so the actual from the inside out The pressure drop is faster and the actual pressure drop curve should be as shown by the dotted line in Figure 5 instead of the solid line. Since the area formed by the entire curve and the abscissa represents the raised load and the tube load is constant (6) calculated value is greater. Coupled with a certain loss of pipeline resistance and other reasons, resulting in the actual "high pressure" value than the formula (6) calculated value higher than the value of the "high and medium pressure" According to the experience of multiple commissioning, the actual average of the four Tuowa "high and medium pressure" is about 1.5 times of the calculated value of (6).

Theoretically selected high-pressure pump to allow the peak pressure should be greater than the "high pressure", the pump rated pressure should be greater than the "high pressure." However, the actual situation from the scene to debug, the actual "high pressure" than the theory of "high pressure" is much smaller, so the pump selection, if similar debugging data, you can also choose to allow the peak pressure is less than the theoretical "high pressure "Pump, but should be limited, and the pump rated pressure must be greater than the" high pressure ", at least should be calculated (6) more than 2 times.

The minimum thickness of the hydrostatic oil film between the slip ring and the treadmill shall be not less than 0.1 mm. If the working fluid viscosity (ie, the working temperature range) and the weight of the mill are determined, ) It is easy to calculate the amount of pump required.

4 interlock control and set value to determine

The high pressure oil supply system of the electrical contact pressure gauge (or pressure relay) is used to monitor the oil pressure of the high pressure circuit Tawat oil chamber. When the oil pressure rises to "high pressure" after the tube mill, the oil pressure drops to a steady value (high pressure), forming a hydrostatic oil film, during which the pressure gauge pointer over immediately falls back to "high pressure "And" high and medium pressure "between the upper limit set value, the interlock control in the computer over the upper limit set the value of the best" memory ", and drop the set value after the start of the launch tube mill signal of. Some control only use as long as the pressure gauge pointer exceeds the upper limit set value after the start of the mill, this control will cause if the safety valve set pressure does not exceed the "high pressure" but more than the pressure gauge upper limit set value (Such as the mill is not raised), of course, this situation is not properly adjusted safety valve set pressure or safety valve performance instability may occur. The lower limit set value is set at a value lower than the "high and medium pressure" (high and low pressure), if the system due to pump failure or tubing cracking caused by oil pressure drop below the lower limit set value, the alarm signal and stop Tube mill.

In this paper, the upper limit of the electrical contact pressure gauge (or pressure relay) can be set at about 5MPa higher than the actual "high and medium pressure" value; the lower limit setting can be set in the mill to form dynamic pressure oil film After the (high pressure pump has stopped) the value (P dynamic pressure) on or slightly smaller.