Since PTFE has many advantages and excellent performance, rubber is gradually replaced in reciprocating seal. The current reciprocating PTFE seals are:
(1) v-shaped packing seal. Substitute the original rubber clip structure to improve the performance. Donghong produces a product used in the pressure water cutting machine, sealing pressure up to 400MPa, and obtain a very long life.
(2) bowl seal. The PTFE seals produced by donghong fluorine are mainly used in the filling machine.
(3) seal with inner spring. It has low friction coefficient, no creep and slippage in the cylinder. Because the opening end is at the high pressure end, the high-pressure fluid is filled into the cavity, making the sealing pressure more and more tight, no manual adjustment is required. The spring force ensures that the negative pressure is close to the cylinder wall during installation or oil suction. This kind of sealing pressure is very high, up to 400 mpa, wide working temperature (200 ℃ ~ + 260 ℃), can be used in dry friction without oil is normal, allowing high pressure operation. You can pump oil or water and various chemical fluids or gases.
(4) Bla seal. It is a new structure introduced by Bal company in USA. It has a built-in spring, and the outer wall has teeth protruding. Can be reciprocating seal, can also make rotary seal, the working pressure can be up to 700MPa. The opening end of it is toward the high pressure fluid, and the fluid pressure will be pressed tightly. The pressure is concentrated due to the presence of sharp teeth. Multiple gears can reduce the thin film layer by step. In addition, can store lubricants between tooth and tooth, advantageous work.
PTFE seal has been developed for several decades and is becoming more and more perfect. However, it has high production cost, complex process, lack of high elasticity, and can not replace the cheap rubber seal completely. Especially in the sealing water quality of a kind of fluid, it wears a large amount of wear, life is not enough requirements, not completely replace mechanical seal. In order to make the PTFE seal to be more perfect, engineers from all over the world have been research its abrasion mechanism, looking for different filling formula, improving filler material, improve the shaft surface material, believe that in the future there will be a new generation of PTFE seal, it will can meet the requirements of modern machines are increasingly demanding.