AMP_04_May_June_2021_Digital_Edition

FEATURE A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 1 5 9 Typically, when someone thinks of just throwingheatwitha welding torch, the needle valves used to ignite and regulate the flow through the torch are done manually and without any external measurement, so the ignition has no exter- nal control, nor does the application. A professional flame hardener has both. For example, before ignition, machines check to ensure cooling water is flowing through the flame heads (Fig. 7). This prevents a flame head fromoverheating andcausingablowbackthroughthetorchmechanismclose to the operator. The status of the cooling water in the flame head is measured and shown on the operator’s touch screen. Ignition is further controlled by a flame eye sensor that shuts down the machine in the case that the pilot light fails to ignite. For example, oxygen flow is so high it extinguishes the pilot light. The flame eye shuts down the machine before any more fuel gas is released (Fig. 8). It controls the ignition process by making sure there al- ways is flame, and never gas or oxygen being released that isn’t burning. 8 Fig. 5 — In a manual control operation, Dwyer flowmeters indicate the levels of fuel and oxygen coming into the flame head apparatus. If they are too low or too high, the operator needs to adjust the flows using the machine’s needle valves. Fig. 6 — In an automatic operation, mass flowmeters detect the incoming flows of oxygen and fuel and make any necessary adjustments to ensure they deliver the required flows to the flame head before a part can be run. No operator intervention is necessary. Fig. 7 — The human machine interface screen shows a “Head Cooling Flow OK” green indicator, giving the operator assurance about the integrity of the flame head prior to ignition. Fig. 8 — The flame eye controls the ignition sequence to ensure no gas or oxygen will flowwithout being burned. 7