We all know that the hydraulic butt welding of the hydraulic butt welding machine can be divided into successive hydraulic butt welding and preheating hydraulic butt welding. Successive hydraulic butt welding consists of a hydraulic stage and an upsetting stage. Preheating hydraulic butt welding is to add a preheating stage before the hydraulic stage. It heats the workpiece with intermittent current pulses before the hydraulic stage, and then enters the hydraulic and upsetting stage.
(1) Reduce the required power. It can weld workpieces with larger cross-sectional area on a small-capacity welding machine. Because when the capacity of the welding machine is lacking, if the workpiece is not preheated to a certain temperature first, the successive hydraulic processes cannot be stimulated. Preheating is the best way.
(2) Reduce the cooling rate after welding. The hydraulic butt welding machine performs preheating hydraulic pressure, which can make the cooling rate of the workpiece slower, and effectively prevent the quenching deformation and cracks of the quenched steel joint during cooling.
(3) Shorten the hydraulic time. Preheating can shorten the hydraulic time to reduce the hydraulic margin and save precious metal.
Although preheating is a work that the hydraulic butt welder has to do. However, preheating also has certain drawbacks. Including: extending the welding cycle, reducing productivity; making the process of automation more complicated; preheating control is more difficult. If the degree of preheating is different, the stability of the joint quality will be reduced.
The hydraulic butt welding skill of the hydraulic butt welding machine is mainly to use the workpiece counterpart contact resistance to generate heat to heat the workpiece, the metal surface is melted, the temperature gradient is large, and the heat-affected zone is relatively small. The hydraulic process has the self-maintenance function of exhausting air and reducing metal oxidation. Upsetting can also discharge oxides with the liquid metal out of the weld, with fewer defects such as impurity and incomplete penetration of the weld. The hydraulic process has a strong self-regulating function, lower requirements for strict compliance with standards, and stable welding quality. The electric power required per unit welding cross-sectional area is small, and only (0.1-0.3) KVA/mm2 electric power is required for welding mild steel. Most industrial welding machine suppliers will choose hydraulic butt welding machines.
The weld is to form a common crystal grain under the condition of plastic deformation of the counterpart solid metal of the workpiece. The hydraulic butt welder has a high welding yield, and it only takes a few seconds to tens of seconds to weld a joint. Welding has a wide range of applications. In principle, all metal materials that can be cast can be welded by hydraulic butt welding. For example, low-carbon steel, high-carbon steel, alloy steel, stainless steel and other non-ferrous metals can be welded by hydraulic butt welding. The welding cross-sectional area is large, generally from tens to tens of thousands of mm2 cross-sectional area can be welded. Hydraulic butt welders are widely used for welding various plates, pipes, profiles, solid parts, tools, etc., and are widely used. This is an economical, high-power welding method.