Tham khảo tài liệu 'advanced welding processes episode 2 part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 204 Advanced Welding Processes b Safety The collision between the electron beam and a metal surface will generate x-rays suitable screening is incorporated in the equipment to ensure that the operator is not exposed to this secondary radiation. c Joint configuration The joint configurations are usually variants of square butt lap and stake welds as previously shown in figure . Again accurate positioning and joint preparation is usually necessary due to the small spot size. Developments Although the basic process has remained unchanged for many years some significant advances have been made in the maximum power available the operating techniques and the equipment. a EBW beam power Whilst for many applications beam powers of up to 25 kW are quite adequate there has been an attempt to extend the weldable thickness range particularly for out of vacuum applications and systems with output powers up to 200 kW have been built. b Chamber loading systems The chamber loading time may be considerably reduced particularly for large volumes of small components by using an integrated loading system incorporating vacuum seals and progressive pressure reduction. The shuttle transfer system developed and patented by Wentgate Dynaweld is illustrated in figure and involves the use of custom-designed workpiece carriers into which the component to be welded is loaded. The carrier or shuttle which is fed into the welding chamber via a feed tube are equipped with O rings which seal the enclosure and allow pre-evacuation. c Vapour shields and beam traps The collection of metal vapour inside the electron gun can cause unstable operation and mechanical shields are often incorporated in the system in an attempt to exclude vapour from the gun area. A further improvement in this area is the development of the Electron Gun Shuttle transfer tube Loading breech pj8ton B Piston A shaft Work Moving Pneumatic actuator Servo positioner Pre-evacuation port Chamber Figure Shuttle .
