Gear pump is ideal for conveying high viscosity liquid equipment, its wide range of applications. At present, although domestic enterprises have produced many gear pumps suitable for conveying high-viscosity liquids, some problems still exist in material selection, leakage and noise prevention due to imperfect testing methods. Especially domestic high-viscosity gear pump in the efficiency, reliability and service life and other aspects of foreign products there is a big gap. Therefore, the majority of high-viscosity gear pumps used in China's oil and chemical industries still rely on imports. The development of high-viscosity gear pump at home and abroad are as follows: Gear Structure: Gear of high viscosity gear pump common spur, helical, herringbone, helical teeth, tooth profile are mainly involute and arc type. Usually small gear pump to use more involute spur gear, high temperature gear pump often use variable gear, conveying high viscosity, high pressure melt melt melt more use of involute helical gears. Gear and shaft made of one, its rigidity and reliability is higher than gear and shaft separately manufactured gear pump. Foreign low-pressure gear pump gear is often used square structure, that gear tooth width equal to the addendum circle diameter. The high-pressure occasions used in high-viscosity gear pump gear tooth width less than its tip diameter, which is to reduce the gear radial compression area, reduce gear, bearing load. Pump and heating method: In general, the heavier the gear pump pump housing, the higher the temperature resistance, compressive strength. Pump material commonly used ductile iron, cast aluminum alloy can also be cast using hard cast, or extruded aluminum alloy profiles manufacturing. When the medium is corrosive, high-cost stainless steel can be used. Foreign high viscosity gear pump to use more nickel, chromium alloy steel as the pump casing material, this material in the strength, reliability and cost of the overall performance is better. In order to solve the trapped oil phenomenon of the gear pump, a symmetrical unloading groove is usually provided on the pump cover, or an asymmetric unloading groove is opened to the low pressure side, a taper unloading groove is adopted on the suction side, and a rectangular unloading Depth of the groove, unloading groove than the hydraulic pump used in industrial gear deeper. Due to the high viscosity of the medium fed by the gear pump, the media must be heated or insulated in order to reduce flow resistance and increase the suction capacity of the pump. Heating elements are usually used to make viscous liquid heat evenly. If the temperature fluctuations, the delivery of high-viscosity liquid prone to degradation, it is recommended to use fluid heating, especially large displacement gear pump. Fluid heating is divided into built-in, external structure. The so-called built-in means gear pump, according to the specific circumstances of the media. Built-in for the delivery of liquid temperature uniformity is higher, or require uniform cooling of high temperature liquid occasions. When the lack of electrical heating or security requirements of the temperature control is not high, the external structure can be used.