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The heat-treating production line
The hardening process. The conveyor furnace process hardens the steel to about 60 Rockwell scale.
1. Knife blanks are cut to length using metal cutting saws.
2. The heating section in the Abbott conveyor tunnel furnace. Blades enter on conveyor belt in table at right. The hardening temperature is about 1850°F. 3. The air quenching (cooling) portion in the conveyor tunnel furnace. Blades are rapidly cooled to about 120°F. They exit on conveyor at left, where they are placed in racks for tempering.
The tempering process releases stresses formed during hardening, making the blades less brittle. Rockwell hardness decreases about 4 units. These are the box ovens visible in the walk-through.
5. Hardened knife blanks go to the tempering ovens next. They must be tempered twice, for about 2 hours each time, at different temperatures.
4. Knife blanks awaiting tempering in racks . They should spend no more than 45 minutes at room temperature before tempering. Each rack can hold 24 – 7.66" blades. 12 racks can fit in the box ovens at a time.
7. Small box furnace. The tempering ovens are normally kept at temperature, so are open only for loading or for service. The alarm light will flash and a buzzer sound when it is time to remove the blades. Too long in tempering will reduce hardness excessively. Three tempering ovens handle the output from the conveyor furnace hardening process. Two of them are shown above. Each oven has a control panel for setting heating time and temperature. 8. The hardened and tempered blanks are now fully heat treated. After a final inspection the blades are shipped to the customer.
Finishing and shipping The hardened blades are ground to final shape and sharpness,
inspected, and shipped to customers world wide.
10. Finished blades. The true proportions have been altered in this picture.
9. After inspection the hardened blades go to surface grinding for final shaping.The picture shows a window into enclosed surfacing wheel. The coolant keeps the blades from heating and carries chips away.
11. Blades in boxes ready to ship.
12. A cnc (computer numerical control) cutoff saw cutting small blades. This is the saw modeled in the simulation. The saw in figure 1 is similar but is controlled by screw adjustment rather than electronically.
The bar stock enters at left. The low growling sound is the saw cutting into the bar stock. Liquid cools the blade. The moving tray at right sorts cut blades in bins by size.
Process Simulation Home Page