Manufacturing process characteristics of dustproof ring

The correct choice of the main and auxiliary materials is an important condition to ensure the working ability of the dust ring. Nitrile rubber can work in -30 ~ +80 ℃, short-term 100 ℃ in oil, emulsion, fuel and water. Butadiene rubber dust ring can work in acid, alkali dilute solution, low temperature limit -50 ℃. Fluorine rubber than the above two rubber chemical stability and temperature resistance is high, but cold resistance and process is poor. Polyurethane dust ring strength and tear resistance, wear resistance, high performance, but heat resistance, cold resistance, water resistance is not enough, expensive, processing difficulties, limiting its widespread use. Rubber fiber material with high strength, is a promising material for dust rings. The Soviet Union manufacturing dust ring using four groups of rubber materials, its performance is shown in Table 2.

　　In addition to rubber, the production of dust ring materials are rubber liquid φ3H-1, 9M-35φ, metal skeleton, skeleton rust remover, mold washing agent, mold release agent, skeleton cleaning agent, etc. Although the rubber fabric dust ring has high durability under severe use conditions, it has not been widely used because of laborious production. Manufacturing TOCT24811-81, 3 type dust ring polymer scraper materials are fluoroplastic φ-4; polyimide 610 casting type, 12 (IIA12-10) (CCT6-05- 425-76), 6(IIA-210/310)(OCT6-06-C9-36) and 6 block (Kaplon B)(TY6- -05--988--78); thermoplastics (TY6-05-211- 1291-82), etc.

　　Metal springs should be stable to the internal and external media corrosion, and in the use of temperature range stiffness characteristics do not change significantly in the manufacture of materials, spring ring preferably made of stainless steel, using mild steel should be chromium or cadmium plating, the thickness of the coating is not less than 15 μm. manufactured spring ring should be tested for stiffness, diameter and strength of the joint. The standard of oil seal spring (TOCT8752-79) can be used to design and manufacture the spring ring of dust ring. The requirements for other forms of springs are similar, but springs buried in the rubber matrix, the corrosion resistance requirements can be reduced, which is the same for the accessories used to stretch the dust ring during assembly. If the rubber ring as a spring element, the material should meet the following requirements: stable to the surrounding medium, according to TOCT9030-74 swelling is not greater than ± 5%; 70 ℃ aging 144h tearing elongation coefficient (TOCT13808-79) is not less than 0.2. In the dust ring throughout the use of the rubber ring should Generate enough stress to make the lip of the dust ring to the live rod compression, and a high recovery rate to ensure that the lip of the movement of the live rod continuous and dense tight.

　　The following requirements for the metal used in the manufacture of the attachment: easy stamping and forming, ability to spray noisy and electrochemical treatment, polishing, high adhesive strength to rubber, corrosion resistance.

Composite dust ring structure with external floating bushing

　　Figure 33 Composite dust ring structure with external floating bushings

Installed in the hydraulic fluid action measurement of the dust ring

　　Fig. 34 Dust ring installed in the hydraulic fluid action test (1) structure

　　Dust ring is generally molded process, the main process is, preparation of semi-finished products, molding vulcanization, finished machine processing. Production of skeleton dust ring, to prepare and treat the metal skeleton before vulcanization, in order to obtain high bond strength with rubber, in the manufacture of TOCT24811-81 and OCT38.05337-85 dust ring, has developed a unified process document ETF51- 40138=84, according to which manufacturers can draw up the best process according to the existing equipment.

　　The equipment, tooling and tools used in the production of dust rings are as follows: a hot foot material opener, a precision preformer for the manufacture of semi-finished products, a column press for the manufacture of semi-finished fluoroelastomer profiles, a flat vulcanizing machine, a punching machine for cutting semi-finished products, a die loading and unloading device for the use of cassette molds, a surface grinder for grinding dust rings, a facility for pressing out and cutting semi-finished products, a device for opening and removing dust rings, a device for removing and grinding edges, etc. Vulcanizing abrasives, scissors, chemical storage containers, etc.

　　The rubber is stored in the warehouse at 0~25℃, avoiding direct sunlight, not in contact with oil, fuel and other substances that can destroy rubber, and the stock period of rubber is not more than 4 months for NPH-1314, 3 months for 3825 rubber, 3 months for KP360, and 4 months for B-14 -1 for four months.

　　Extrude the type surface rubber strip or rubber ring by precision preformer, press out the type surface rubber strip by press out machine or injection machine, then cut out and punch out the semi-finished products from the rubber sheet by punching knife. The weight of semi-finished products is 2 - 10%. Semi-finished products are wrapped with polyethylene film or PVC film and stored for no more than 6d. The metal skeleton should be de-oiled before use, and if rust is found, it should be de-rusted and cleaned and dried.

　　The metal skeleton bonded with NPH-1314 glue is made of φ∈H-1, 51-K-20 or 9M-35φ glue, while other glue is made of φ∈H-1 and 51 -K-20; these two types of glues are applied to the phosphate treated skeleton.

　　The 9M-35φ glue solution is applied on the skeleton which is cleaned by sandblasting (air pressure 0.4~0.6Mpa) and gasoline and subsequently dried.

　　The sandblasted skeleton should be kept in gasoline for no more than 24h, and the skeleton coated with glue should be kept for no more than 4h before vulcanization. the contaminated mold is chemically cleaned in a hot alkali bath. The mold after vulcanization of fluorine rubber containing copper salicylic fork imide can be quickly cleaned with 10~25% aqueous ammonium hydroxide solution to remove the dirt. Any kind of lubricant such as silicone oil, emulsion, 12φ emulsion, potassium stearate solution can be applied on the surface of the mold cavity before vulcanization, and 6C diameter K-180-05 lubricating mix is recommended for NPH-1314 rubber.

　　The vulcanization conditions of each rubber standard specimen are shown in Table 3. Sometimes the dust ring has to be removed from the film cavity by compressed air. Manufactured products are ground or cut lips and removed from flying edges and stored in packing boxes.

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