Definition of multi-way valve

Multi-way valve refers to a multi-way combined valve composed of two or more reversing valves as the main body, and according to different working requirements, plus auxiliary devices such as safety valve, one-way valve, oil filling valve and so on.

The reversing valve can be divided into manual, motor, electromagnetic, hydraulic, electro-hydraulic, pneumatic, etc. according to the way of operating the movement of the spool. The reversing valve is a valve that uses the spool to make relative movement in the valve body hole to connect or cut off the oil circuit to change the direction of oil flow.

The multi-way reversing valve is a collective valve composed of several one-way reversing valves, safety relief valves, one-way valves and oil filling valves. It has the advantages of compact structure and small pressure loss.

The multi-way reversing valve control circuit can control the movement of multiple execution units, and is mainly used in construction machinery, crane conveyors and other mobile machines that require centralized control of the movement of multiple execution units. The control method is mostly manual control. When the working pressure is high, the pilot control of the pressure reducing valve is used.

The multi-way reversing valve control circuit is divided into three basic oil circuits: series, parallel, and series and parallel according to the connection mode.

According to the different structure of the web part of the paper machine, the paper machine can be divided into: long web type, round web type, clip web type, stacked web type and with finishing roller type.

The paper machine can be regarded as a kind of linkage machine composed of several equipments. Usually it can be divided into two parts: wet end and cadre. The wet part includes the pulp conveying equipment, the mesh part and the pressing part; the cadres include the drying part, the calender and the paper coiler.

After sizing, sizing, filling and purification, the pulp with the properties suitable for paper making enters the pulp conveying equipment of the paper machine at the concentration of 0.3% - 1.3%. Then, the paper flows evenly and stably to the net surface of the forming net after being distributed and leveled by the pulp distributor and the headbox. After the pulp is fed into the net near the center line of the chest roll, it is gradually filtered and dehydrated to form a continuous wet web. The net table is usually equipped with table roll, vacuum water suction tank, couch roll and other forming dehydration elements. When the wet web is dehydrated to a certain degree of dryness (usually about 20%), it can be peeled from the mesh and sent to the pressing part for further dehydration.

The press section of paper machine is composed of several groups of roller press. The wet web is dragged by the press blanket and dehydrated by mechanical extrusion between the press rolls. In order to maintain the good dehydration performance of the press blanket, the press upper roller is equipped with a blanket washing device. After pressing, the dryness of wet web can reach about 40%.

The wet web is further dehydrated on the paper machine, usually by heating and evaporation. The drying section of paper machine usually consists of many drying cylinders heated from the inside by steam. The drying cylinder is covered with dry blanket (or canvas, dry net), which aims to press the web tightly onto the cylinder surface, improve the heat transfer efficiency and improve the surface quality of the web.

After drying, a calender consisting of 6-8 rollers is usually used to improve the surface quality of the web.