Welded Hydraulic Cylinders
Automotive, agriculture, construction, material handling, aeronautics and transport industries among others utilize welded hydraulic cylinders in a variety of machines and equipment. Cranes, bull dozers, excavators, elevators, lifts, road graders and forklifts all operate with the help of hydraulics. While welding is only one assembly technique, it has several advantages over the alternative tie rod hydraulic cylinders. Because the barrel is welded directly to the end caps, the devices can handle very high pressure applications. While tie rods offer heavy duty hydraulic cylinders as well, they have a much larger diameter. Welded models offer the same strength but are compact enough to be easily integrated into small, mobile and confined machines. Welding is also well suited to customization. Special features such as additional ports, custom mounts and valve manifolds are easily adjoined. The smooth outer surface created by welding also makes multi-stage telescopic cylinders possible.
Welding is a process that joins materials by causing coalescence through heat, pressure or both. In the case of hydraulic cylinders, the metal end caps are welded to the cylinder barrel. This creates a tight seal that is able to withstand the tremendous force encountered by industrial hydraulic machines. The ports, located at either end of the cylinder, are also welded in place. The tube shaped barrel may be welded, though it is more often formed by rolling or extrusion processes to avoid a seam. As welding is permanent, the front rod glad is usually threaded or bolted into the head of the cylinder to allow piston and rod servicing. Despite these differences, the general function of the welded hydraulic cylinder is similar to that of all cylinders. Hydraulic fluid is pressurized and released into the enclosed cylinder barrel. The fluid engages the piston, a disc-shaped device that divides the chamber into two compartments. The piston is attached to a rod which protrudes from the barrel and is attached at the opposite end to the machine linkage or work load that is to be moved. Introducing fluid below the piston extends the rod, while pressure above the piston retracts it. The materials used in the construction of hydraulic cylinders must be compatible with the hydraulic fluids they will encounter as well as able to withstand the wear and friction created during use. For this reason durable metals such as bronze, aluminum, steel and iron are most often used. Chrome plating or ceramic coatings may also be used to increase product longevity. While stainless steel is a popular material for hydraulic cylinders, it should not be used with welding as it is prone to distortion and cracking when heated.
