Hydraulic press: A hydraulic press is a machine that uses hydrostatic pressure to process metal, plastic, rubber, wood, powder and other products. It is often used in pressing process and press forming process, such as: forging, stamping, cold extrusion, straightening, bending, flanging, sheet deep drawing, powder metallurgy, press fitting and so on.
Its principle is to make use of Pascal's law to make use of hydraulic pressure transmission machinery, there are many types. Of course, the uses are also diverse according to needs. For example, according to the type of liquid that transmits pressure, there are two major categories: hydraulic press and hydraulic press.
The total pressure generated by the hydraulic press is relatively large, and it is often used for forging and stamping. Forging hydraulic press is divided into die forging hydraulic press and free forging hydraulic press. The die forging hydraulic press uses abrasive tools, while the free forging hydraulic press does not use molds. The first 10,000-ton hydraulic press manufactured in my country is a free forging hydraulic press.
principle
The working principle of hydraulic press. The areas of the large and small plungers are S2 and S1 respectively.
The force is F2 and F1 respectively. According to Pascal's principle, the pressure of a closed liquid is equal everywhere, that is, F2/S2=F1/S1=p; F2=F1(S2/S1). It represents the gain effect of hydraulic pressure. Like mechanical gain, the force increases, but the work does not gain. Therefore, the movement distance of the large plunger is S1/S2 times the movement distance of the small plunger.
The basic principle is that the oil pump delivers the hydraulic oil to the integrated cartridge valve block, and distributes the hydraulic oil to the upper cavity or lower cavity of the cylinder through various one-way valves and overflow valves, and makes the cylinder move under the action of high pressure oil. It is a device that uses liquid to transmit pressure. When liquid transfers pressure in a closed container, it follows Pascal's law. The hydraulic transmission system of a four-column hydraulic press consists of a power mechanism, a control mechanism, an executive mechanism, an auxiliary mechanism and a working medium. The power mechanism usually uses an oil pump as the power mechanism, which is generally an integral oil pump. In order to meet the requirements of the moving speed of the actuator, one oil pump or multiple oil pumps are selected. Gear pumps for low pressure (oil pressure less than 2.5MP); vane pumps for medium pressure (oil pressure less than 6.3MP); plunger pumps for high pressure (oil pressure less than 32.0MP). Pressure processing and forming of various plastic materials, such as extrusion, bending, deep drawing of stainless steel plates and cold forming of metal parts. It can also be used for pressing powder products, grinding wheels, bakelite, and resin thermosetting products.
Classification
According to the structure, it is mainly divided into four-column type, single-column type (C type), horizontal type, vertical frame, universal hydraulic press, etc.
According to the purpose, it is mainly divided into metal forming, bending, stretching, punching, powder (metal, non-metal) forming, press fitting, extrusion, etc.
Hot forging hydraulic press
The large hydraulic forging press is a forging equipment that can complete various free forging processes and is one of the most widely used equipment in the forging industry. At present, there are forging hydraulic presses of 800T, 1600T, 2000T, 2500T, 3150T, 4000T, 5000T and other series specifications.
Four-column hydraulic press
The hydraulic press is suitable for the pressing process of plastic materials. Such as powder product molding, plastic product molding, cold (hot) extrusion metal molding, sheet stretching, and horizontal pressing, bending pressing, turning through, correction and other processes.
Four-column hydraulic press can be divided into four-column two-beam hydraulic press, four-column three-beam hydraulic press, four-column four-beam hydraulic press, etc.
Single arm hydraulic press (single column hydraulic press)
The working range can be expanded, the three-sided space is used, the stroke of the hydraulic cylinder is lengthened (optional), the maximum retractable is 260mm-800mm, and the working pressure can be preset; the heat dissipation device of the hydraulic system.
Gantry hydraulic press
The machine parts can be assembled, disassembled, straightened, calendered, stretched, bent, punched, etc., truly realizing one machine with multiple functions. The working table of the machine can move up and down, and the size has expanded the opening and closing height of the machine, making it more convenient to use.
Double column hydraulic press
This series of products are suitable for pressing, bending and shaping, embossing and creasing, flanging, punching and shallow drawing of small parts of various parts; forming of metal powder products and other processing techniques. It adopts electric control, is equipped with inching and semi-automatic circulation, can hold pressure and delay time, and has good sliding block guidance, convenient operation, easy maintenance, economical and durable. According to the needs of users, functions such as thermal instrument, ejector cylinder, stroke digital display, and counting can be added.

Mechanical presses have greater impact and are more suitable for separation processes such as punching and cutting.
The hydraulic press has relatively stable loading and is suitable for forming processes such as bending, deep drawing, and shaping.
The above is the opinion of most people, but Japanese research results show that the deformation of stamping parts is basically independent of the stamping speed, only when the stamping machine reaches more than 2000 times per minute, it will have an impact.
In terms of efficiency, mechanical presses should be higher.
In terms of reliability, mechanical presses are relatively solid, while hydraulic presses are generally prone to hydraulic problems such as oil leakage.
In summary, it is better to use a mechanical press in addition to the procedures of shaping and correcting bending, which facilitates the improvement of work efficiency.

The press (including punches and hydraulic presses) is a universal press with exquisite structure. It has a wide range of uses and high production efficiency. The press can be widely used in cutting, punching, blanking, bending, riveting and forming processes. By applying strong pressure to the metal blank, the metal is plastically deformed and fractured to be processed into parts.
Hydraulic press is a machine that uses liquid as working medium and is made according to Pascal's principle to transfer energy to realize various processes. The hydraulic press is generally composed of the machine (host), power system and hydraulic control system.

1. Various components of hydraulic transmission can be conveniently and flexibly arranged according to needs.
2. Light weight, small size, small movement inertia, and fast response speed.
3. Convenient operation and control, which can realize stepless speed regulation in a wide range (speed regulation range up to 2000:1).
4. The overload protection can be realized automatically.
5. Generally, mineral oil is used as the working medium, the relative moving surface can be lubricated by itself, and the service life is long.
6. It is easy to realize linear motion.
7. It is easy to realize the automation of the machine. When the electro-hydraulic combined control is adopted, not only a higher degree of automatic control process can be realized, but also remote control can be realized.

According to the structure, it is mainly divided into: four-column hydraulic press, single-column (c-type) hydraulic press, horizontal hydraulic press, vertical frame hydraulic press, etc.
According to the purpose, it is mainly divided into metal forming, bending, stretching, punching, powder (four-column hydraulic press metal, non-metal) forming, pressing, extrusion, etc.

The hydraulic machine uses hydraulic oil, and the viscosity (32, 46, 68, etc.) and specifications (HL, HM, HV, etc.) need to be selected according to the equipment requirements. Generally, HM type (anti-wear hydraulic oil) is used. The hydraulic oil is the hydraulic medium used in the hydraulic system that utilizes the hydraulic pressure energy, which plays the role of energy transmission, anti-wear hydraulic oil, system lubrication, anti-corrosion, anti-rust, cooling, etc. in the hydraulic system. For hydraulic oil, first of all, it should meet the requirements of hydraulic device for liquid viscosity at working temperature and starting temperature. Because the viscosity change of lubricating oil is directly related to hydraulic action, transmission efficiency and transmission accuracy, the viscosity-temperature performance of the oil is also required. And shear stability should meet the various needs of different applications. There are many types of hydraulic oils, and the classification methods are different. For a long time, it is customary to classify hydraulic oils according to their uses, and some are classified according to oil type, chemical composition or flammability.