Welding & Automation, Inc. has recently completed a state of the art multi-chambered dry box resistance welding system capable of hermetically sealing glass to metal seal products with up to eight (8) linear inches of lid seal length. The first chamber incorporates a vacuum bake out oven capable of up to 300° C in an inert vacuum atmosphere. The oven is available with a programmable sequencer (mini-PLC) capable of automatically controlling the vacuum levels, the gas purging, the heating cycle, and the venting. Easily accessible water cooled entrance and exit oven doors provide protection for the vacuum seals insuring an air tight chamber, with extended seal life.

The second chamber is a five foot long stainless steel dry box with four glove ports, and a full view front access window for optimum operator visibility. A full length lighting fixture with external lamp accessibility is the illumination source for the dry box. The dry box and oven are supported by instrumentation for controlling the gas flow, the gas mixture, the relative humidity, and the gas quality. The instrumentation includes a digital hygrometer, a dual purge gas flow controller, an oxygen analyzer, a conductivity meter for measuring nitrogen quality, and an automatic gas mixing system. Integral to the box are pressure relief valves to maintain a positive pressure at the desired level. The internal tooling incorporates a precision die set weld head with quick change water cooled electrode holders closely coupled to a 24 tap 200 KVA single phase welding transformer. The die set weld tooling is made to tool and die accuracy within 0.0002” for both parallelism and perpendicularity. When required the power supply can be provided with a 1 KHz mid-frequency power pack. The weld head incorporates a fast follow up programmable spring system capable of exerting up to 8,000 pounds of force on the work. The head force is programmable through the weld control in one pound increments.

The third and final chamber in the multi-chambered dry box resistance welding system is a stainless steel air lock for controlled removal of finished product. The air lock has two doors; one through the interior of the dry box, which acts as a pass through into the air lock without contaminating the dry box environment. The second door is located at the front of the air lock chamber for direct removal to the external environment. The internal air lock environment replicates that of the dry box to prevent internal contamination of the dry box when passing finished product from one chamber to the other.

The above described system offers application solutions wherever high reliability hermetic sealing is required. These systems have been used in the computer, electronics, ordinance, medical, and the automotive industries with consistent success. For more information on equipment of this type, please contact: