高压机械密封的要求

Requirements for high pressure mechanical seals

1.增大密封零件截面

1. enlarging the section of sealing parts

对转动零件的截面要加大，静环也相应有较大的截面，不要在静环外径上有台阶或开槽.但要注意，随着密封面宽度b的增加，热变形和磨损也随之增加，同样要增加压盖的厚度以防变形和能承受压力.使用重载荷弹簧，使用较大直径的销子以适应较大的启动扭矩。

The cross section of the rotating parts should be increased, and the static ring has a larger section. Do not have steps or slotting on the outer diameter of the static ring. However, as the width of the seal is increased, the thermal deformation and wear will increase with the increase of the width b of the seal. The diameter of the pin is adapted to the larger starting torque.

2.提高密封零件的加工精度

2. improve the machining accuracy of sealed parts

(1)压盖底部装静环的幢孔面要保证高的平直度，因为在高压下，任何表面上的高出点会传给静环而引起泄漏;

(1) to ensure the high flatness of the hole surface of the static ring at the bottom of the gland, because the high point on any surface will be transmitted to the static ring at high pressure and cause leakage.

(2)提高密封面内外径和宽度的加工精度，因为在高压时，，密封内外径和宽度的精度对比压的变化有明显的影响.密封端面研磨、.抛光后的粗糙度为Ra0.05~0.025(▽12~▽13)，平直度必须限制在1个光带以内.此外，摩擦端面的垂直度和轴的精度也要相应提高。

(2) improve the machining accuracy of the inside and outside diameter and width of the seal, because in high pressure, the accuracy of the inner and outer diameter and width of the seal has an obvious effect on the change of the pressure. The surface of the seal is lapping, the roughness after polishing is Ra0.05~0.025 (12~), and the flatness must be limited to 1 light belts. The precision of the shaft should also be improved accordingly.

注意在高压下因不同介质所造成的冲刷腐蚀和磨损，图10-12 (a),  (b)表示不同摩擦副材料在不同的转速下介质为烃和水及水溶液时压力与密封尺寸的关系。

Attention is paid to the erosion and abrasion caused by different media at high pressure. Figure 10-12 (a), B indicates the relationship between pressure and seal size of different friction materials at different rotational speeds when the medium is hydrocarbon and water and water.

5、采用流体动压式机械密封

5. Using fluid dynamic mechanical seal

流体动压式(也称流体动力式，热流体动压式)机械密封是考虑在高压和摩擦热的情况下，密封缝隙中的润滑膜稳定性而研制成的新型密封面结构，图10-13(a), (b)是热流体动几式机械密封槽的布置图，这种结构类似形式很多(见图4-8)，它的热流体动力效应是在密封上形成，在密封环旋转的时候，槽能使液体强烈地冷却距它较远的密封表面。进行这种冷却时，在密封环的初始表面上形成与槽数相等的流体动力楔和高压区.由于切向流和压力降，在每一个槽后形成慧星状润滑楔(图10-14).因此，随着密面上载荷与滑动速度的增加，摩擦系数反而减小

Fluid dynamic pressure (also known as fluid power, hot fluid dynamic pressure) mechanical seal is a new type of sealing surface, which considers the stability of the lubricating film in the sealing gap under high pressure and friction heat. Figure 10-13 (a), (b) is the layout of a few types of mechanical seal grooves in the heat flow body. This structure is similar in many similar forms (see Figure 4-8). Its thermal hydrodynamics effect is formed on the seal. When the sealing ring rotates, the tank can make the liquid cool the sealing surface far away from it. On the initial surface of the seal, the fluid dynamic wedge and the high pressure area are formed on the initial surface of the seal ring. The comet shape lubricating wedge is formed after each slot (Figure 10-14). As the load and sliding speed increase, the friction coefficient decreases as the tangential flow and pressure drop.