In the hydraulic system and its system, the sealing device is used to prevent the leakage of the working medium and the intrusion of external dust and foreign matter. The element that acts as a seal is the seal. External leakage will cause waste of working medium, pollute the machine and the environment, and even cause mechanical operation failure and equipment personal accidents. Internal leakage will cause the volumetric efficiency of the hydraulic system to drop sharply, failing to reach the required working pressure, or even unable to work. The tiny dust particles intruding into the system can cause or exacerbate the wear of the friction pair of the hydraulic components, and further lead to leakage. Therefore, seals and sealing devices are an important part of hydraulic equipment. The reliability and service life of its work is an important indicator to measure the quality of the hydraulic system. Except for gap seals, seals are used to control the gap between two adjacent coupling surfaces below the minimum gap through which the liquid to be sealed can pass. In the contact seal, there are two types of self-sealing compression seals and self-sealing self-tightening seals (ie lip seals).

Hydraulic presses are suitable for almost any process that requires pressure machining. At present, hydraulic presses are mainly used in the following fields: ① The stamping and deep drawing process of sheet metal parts is mainly used in the forming and processing of metal covering parts in the automobile and home appliance industries; ② Pressure forming of metal mechanical parts, mainly including die forming, extrusion forming of metal profiles, hot and cold die forging, free forging and other processing technologies;

According to the classification of structure, hydraulic presses mainly include single-column hydraulic presses, four-column hydraulic presses, frame hydraulic presses and other hydraulic presses. The single-column hydraulic press can be divided into two structures: the whole body and the combined body. During the work of the single-column hydraulic press, due to the deformation of the body, the slider and the table will have a certain angle, so it is mostly used for low precision requirements. applications, such as: press-fitting, sheet pressing, straightening and other processes.

1) Hydraulic presses or automatic production lines equipped with automatic loading and unloading devices will become the development direction of hydraulic presses in the future. At this stage, due to labor costs and technical problems, domestic enterprises mostly use manual loading and unloading. But in some developed countries, automatic production lines were basically popularized in the 1960s and 1970s.

There is still a big gap between the production technology level of local hydraulic enterprises in my country and foreign advanced enterprises. Local hydraulic companies have insufficient independent innovation and R&D capabilities, and most of the hydraulic products they produce are at the middle and low end of the value chain. The development of high-end hydraulic components lags behind the downstream equipment manufacturing industry. Domestic host manufacturers cannot purchase high-end hydraulic products from local hydraulic companies. As a result, a large number of high-end hydraulic components need to rely on imports.

(1) Strong support from the national industrial policy As an important supporting industry for the equipment manufacturing industry, the state attaches great importance to the development of the hydraulic industry. The "14th Five-Year" Development Plan Outline of the Hydraulic, Hydraulic and Pneumatic Sealing Industry and other policies proposes to concentrate advantageous resources to tackle key components, parts and basic materials and other key core technologies; Components, basic software, basic materials, basic processes and industrial technology foundations and other bottlenecks and shortcomings; in-depth implementation of intelligent manufacturing and green manufacturing projects, development of new service-oriented manufacturing models, and promotion of high-end, intelligent and green manufacturing; in-depth implementation of enhanced manufacturing The core competitiveness of the industry and the technical transformation project are encouraged to encourage enterprises to apply advanced and applicable technologies, strengthen equipment renewal and the large-scale application of new products: cultivate advanced manufacturing clusters, and promote the innovation and development of construction machinery and other industries. National and local government departments have given great help in policy support, industrial projects and other aspects, creating favorable conditions for the development of the industry.