Electric Beam Machining (EBM) is the process of thermally changing the kinetic energy of electrons into heat at a higher rate, so by locally heating we can proceed in many directions. different thermal processing methods. Use this method to outsource hard-to-machined parts using traditional methods. Particularly, electron beam welding technology is superior in the processing of hard materials, fireproof and other ceramic materials.
Welding power is achieved by electron beam with a large cross-sectional dimension ranging from a few dozen to several hundred millimeters, but the energy density is small at 105, 107 W / cm2 and the power dissipation power is high. hundred to tens of kw. This beam is projected to the junction between the components and heat it to the melting point. A clean, electronically-free beam of electrons, impurities and oxides. Welding energy is smaller than other welding methods due to the high concentration of energy at the center of the electron beam.
Electronic welding equipment for welding metal can be divided into two types:
– Low voltage equipment, working with accelerating voltage up to 15 – 20 kV.
– High voltage equipment, working with accelerating voltage up to 150 – 200 kV.
The structure of electronic beam welding equipment is not much different than that of other electronic beam equipment. Some special parts of the equipment are vacuum chamber with vacuum pump system, electronic launcher with high voltage DC.
Vacuum chambers are usually equipped with a cooling water system, a cathode power supply system, a magnetic induction system, etc. Vacuum chambers are equipped with special doors to enable the machining parts and Tools for the technological process. Also around the chamber are fitted vacuum measuring instruments in different parts of the chamber.
Typically, the depth of molten metal when electron beam welding can reach about 20 times greater than the welding width. Hence the metal’s ability to stick to depth is better than the width. The depth of the molten metal when soldering depends on the voltage V, the current I, the welding speed and the melting point of the metal.
An important feature of electron-beam welding by electrons is the very high heating and cooling rates. The heating rate can reach 7000oC / s and coolant speed is 1200oC / s. Due to the high concentration of energy, the heating rate and the rapid cooling rate, the heating of the surrounding areas is relatively small. Normally, the temperature in the area of 1.5 mm thick is less than 400oC. should not affect deformation.
If the trace size of the electron beam is from a few centimeters to one millimeter, it does not require a high energy concentration, a typical low voltage of 15-20kV. Conversely, if the requirement for large amounts of energy is reached to achieve a small welding spot, a working voltage of 150-200 kV is required.
Electron beam welding does not necessarily involve the use of equipment that avoids the effects of a jet of heat that is more than 1 mm thick. If the weld is less than 1mm, the technical conditions will be more complicated, so you need to have a device to prevent jealousy.
In general, electron beam welding uses less energy than other methods. This can be explained by the ability to focus energy on the welding position. Because the size of the weld can reach about 10mm, the energy density can reach 107 – 109 W / cm2, which is much higher than the arc welding method (density is about 103 – 105W / cm2). ) and welding (density of 102 – 104W / cm2).