Before installing, check the surface quality of the sealing piece, not to have the flying edges, burrs, cracks, cutting edges. Porosity and loose defects, sealing pieces of geometric dimensions and accuracy must meet the standard requirements. The combined sealing rings of holes are made up of O-ring and wear-resisting rings. Because the O-ring elastic, the installation is relatively easy, and the wear ring elasticity is poor, if the direct installation of the piston steps, grooves easily scratched its sealing surface, affecting the sealing effect. In order to ensure that wear-resistant rings are not damaged when installing, you should take certain installation measures. Wear-resisting ring is mainly made of filled PTFE (PTFE) materials, with corrosion-resistant characteristics, thermal expansion coefficient of large, so before installing the oil in 100 ℃ to soak the 20min, so that it gradually softened, and then use the tooling to plug it in the groove of the piston. Consisting of a positioning sleeve and a swelling sleeve. The positioning sleeve has a head of 5 º chamfer, used to guide the O-ring and wear-resisting ring to the piston end groove. The sheath is made of a better elastic 65 mn Steel by heat treatment, which is processed into a homogeneous symmetrical 8-lobe structure. It is important to note that processing the bottom of the small holes, the degree to evenly, milling open each flap should make the sawing hole at the center of the small holes in order to ensure that the flap can be evenly rising. At the same time all parts should be (smooth) chamfer, lest damage seal ring.
Each type of sealing ring should have a corresponding fixture to ensure its assembly requirements. After the installation is complete, the sealing ring is not allowed to wrinkle, distort, scratch and load reverse phenomena exist. The threaded holes on the cylinders of the hydraulic cylinder are often arranged after the welding process, which inevitably produces burrs at the junction of the threaded hole outlet and the inner wall of the cylinder. In order to remove Burr, it must be designed to make special cutter for its processing, to achieve smooth transition. The structure of the special cutter is shown in Fig. 4. When used, the knife rod is inserted from the threaded hole, and then the cutter head is mounted on the knife rod from the side, and the rotary cutter rod can remove the burr and process the smooth and complete surface.
Another type of sealing is polyurethane material of Y-shaped seal ring because of its high hardness, high elasticity, oil resistance, abrasion resistance and low temperature, etc., widely used in hydraulic cylinder. Its inner and outer lip can be made of unequal shape according to shaft or hole, to play the role of sealing and self-protection. Unequal to the high Y-shaped ring, the short lip contact with the sealing surface, the friction resistance is small, wear resistance, long life; long lips and non-relative motion surfaces have a larger preload amount, the work is not easy to flee, because of polyurethane material of the Y-ring hardness High, pre-compression, in the installation, replacement often results in the sealing ring is broken, rolled and bite edges such as damage, thus not to the due sealing effect, even failure. When assembling, we used a screwdriver to seal the lip along the cylinder diameter to pressure, or with a thin wire to seal the outer lip of the ring tight, so that the outer diameter of the cylinder is less than the inner diameter, and then the sealing ring to the human cylinder, then the fine wire out. However, these two methods are easy to scratch sealing rings, resulting in sealing failure, increase maintenance time. In this case, we use 0. LMM thick cold Rolled steel strip or copper peel to cut it into rectangular, its length is equal to the circumference of the Y-ring outer diameter, and then use it to wrap the seal ring tightly, and then 1.1 points to send people hydraulic cylinder cylinder, the outer lip all into the human cylinder and then extract it, the installation effect is better.