[Welcome] [Home] [General Information] [Portfolio of Selected Work: Industrial Systems ] [Academics]

Industrial Systems: Electrode Positioner for Precise Welding of Metal Bellows

Client

Metal Bellows Corporation, Sharon, MA.

Problem

The welding of metal bellows convolutions require extremely precise location of the tungsten electrode needle respect to the convolution joint. In the absence of automatic controls, the postioning must be checked with a microscope every few convolutions. Very small bellows are very expensive because of the intense labor required.

Solution

There are no suitable controls in the market so one must be developed. The electrode must be positioned within 0.0003" of tolerance about the joint. The system developed consists of a linear differential transformer driven through elastokinematic linkages attached to a sensing knife edge engaged by means of a solenoid against the convolutions before welding. The knife is then disengaged after the desired position is obtained and the welding electrode is energized. The sensor signal controls a stepping motor that drives the elctrode. The sensor is all pre-loaded and its parts are play-free to maintain precision. There is no need for lubrication. The whole system is shielded to prevent perturbations from the welding drivesl. The picture below the sensor side uncovered exposing some of the linkages. The knife edge is protected by two guard plates at top.

Picture of the Electrode Positioner for Precise Welding of Metal Bellows
Closeup Picture of the Electrode Positioner for Precise Welding of Metal Bellows