| 摘要 |
<p>A human welder is provided with a helmet or a hand-held shield with an open window. The open window is normally covered by a coloured safety glass held in position by two tension springs. The glass is also mounted on two arms, which are each attached to an armature located in a solenoid. The two solenoids are each fed with electricity by an electronic- or electromagnetic- switching circuit connected to a welding appts. feeding welding electrodes with either a.c. or d.c. When the appts. only provides a low voltage, e.g. an idling voltage, the solenoids are automatically operated to move the glass away from the window, so the welder can see the workpieces. But when the voltage is raised, e.g. to strike the arc, the current to the solenoids is cut off shortly before the voltage is increased, so the springs move the glass over the window. Complete protection for the human face and eyes from harmful radiation and weld spray.</p> |
