焊接基础知识问答二（Basics of welding Q a two）.doc

焊接基础知识问答二（Basics of welding Q a two） Basics of welding Q a two Three. Welding equipment 1. what is called welding power supply? Answer: welding machine, the supply of electrical energy required for welding, and has suitable for welding electrical characteristics of equipment, known as welding power supply. 2. why have special requirements for arc welding power source? What are the requirements? Answer: in order to ensure the welding arc stable combustion and meet the requirements of various welding process, arc welding power supply has the following special requirements: The static characteristic (or external characteristic) of the arc welding power supply, that is, the relation between the steady output current and the output voltage, has the characteristics of dropping (constant current characteristic) and peace characteristic (constant voltage characteristic). (1). The external characteristics of A, electrode welding, arc welding, TIG welding and carbon arc gouging are characteristics of descent (Heng Liu); The external characteristics of B and CO2/MAG/MIG arc welding power source are flat characteristics (constant voltage characteristics). 2 the dynamic characteristics of arc welding power supply when load state instantaneous changes (such as droplet short circuiting, particle transition, jet transition), the relationship between welding power output current and output voltage and the load transient response ability to use (i.e., to characterize the dynamic response ability), referred to as dynamic characteristics. No-load voltage 3 - indicating voltage before arc striking. Regulation 4 change the external characteristics of the power supply to meet the requirements of the welding specification. 3. why does the arc voltage change when the arc length changes? Answer: determined by the external characteristics of arc welding power, the longer the arc, the higher the arc voltage; the shorter the arc, the lower the arc voltage. 4. why does the current display valu