A hydraulic system can be used for holding and positioning the parts to be welded during a welding operation. It is a typical example of how fluid power can be used in manufacturing and production operations, to reduce the overall costs and to increase production.
This application requires a sequencing system for fast and positive holding. This is accomplished by placing a restrictor (sequence valve) in the line leading to the second cylinder, as shown in Figure 9.5. The first cylinder extends to the end of its stroke.
Oil pressure then builds up, overcoming the restrictor setting and the second cylinder extends to complete the ‘hold’ cycle. This unique welding application of hydraulics was initiated to increase productivity.