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During the second world war (1941-1945), 30% of machine tools used in the United States for hydraulic transmission. Should point out that the development of Japan's hydraulic drive from Europe and the United States and other countries over the past 20 years late. Around 1955, the Japanese rapid development of hydraulic transmission, in 1956 founded the "hydraulic industry would". Nearly 20 to 30 years, Japan's hydraulic drive fast development, has the world leading position.
Hydraulic transmission there are many outstanding advantages, so it has a very wide range of applications, such as general workers. Industry in the plastic processing machinery, pressure machinery, machine tools, etc.; Walk in mechanical engineering machinery, construction machinery, agricultural machinery, automobile, etc.; In iron and steel industry metallurgical machinery, lifting device, such as roller adjustment device; Use the floodgate of civil engineering and levee device, river bridge lifting gear, operating mechanism, etc; Turbine speed regulating device of power plant, nuclear power plant and so on; Ship with the deck of the hoisting machinery (hoist), the bow door, bulkhead valve, stern thruster, etc; Special technology with giant antenna control unit, measuring buoy, lifting revolving stage and so on; Gun control devices which are used for military industry, ship stabilizer, aircraft simulation, aircraft landing gear device release and rudder control device, etc.
The gear pump
The concept of gear pump is very simple, that is, it is the most basic form of two of the same size gear in a close cooperate mutually meshing rotation within the shell, the shell's internal like "8" glyph, two gear in it, the diameter of the wheel on both sides and work closely with shell. Materials from the extruder at suction among two gears, and full of the space, with the rotation of the teeth along the shell movement, finally the two tooth meshing.
Says in terminology, the gear pump is also known as positive displacement device, like a piston within the cylinder, when the fluid of a tooth to another tooth space, the liquid is mechanically squeezed out. Because the liquid is incompressible, so the liquid and the tooth can't occupy the same space at the same time, so that the liquid has been ruled out. Due to the tooth meshing, this phenomenon will continuous happen, as a result, the pump provides a continuous quantity, export pump per turn a turn, the amount of discharge is the same. Along with the continuously rotating drive shaft, pump discharge fluid is constantly. Pump flow is directly related to the speed of the pump. In fact, the pump is very small amount of fluid loss, the running efficiency of the pump can't achieve 100%, because the fluid is used for lubrication on both sides of bearing and gear, and the pump body is impossible without a clearance fit, so cannot make fluid 100% from an outlet, so a small amount of fluid loss is inevitable. Pump can still work well, however, for most extrusion materials, efficiency can reach 93% ~ 98%.
For the viscosity or density change in the process of fluid, the pump is not affected by too much. If there is a damper, such as in the outlet side put a mesh or a limiter, the pump will be pushing fluid through them. If the change in damper work, that is, if the filters become dirty, blocked, or limiter on the back pressure, the pump will maintain a constant flow, until achieve the device in the weakest parts of the mechanical limit (usually equipped with a torque limiter).
For a pump rotation speed, in fact, there is a limit, this mainly depends on the process fluid, if the transmission oil, pump can be rotating at high speed, but when the fluid is a kind of high viscosity polymer melt, this limitation could be greatly reduced. Promote viscous fluid into the suction side of the two tooth space is very important, if not fill the space, the pump can't discharge flow accurately, so the PV value (pressure (velocity) is also a limiting factor, and it is a process variable. Due to these restrictions, gear pump manufacturers will provide a range of products, namely, different specifications and delivery (the amount of discharge by turn every week). The pump will be made to match the specific application process, in order to make system capacity and achieve the optimal price.