Feeder (glass)
A feeder , also called a feeder in German , is the extension of the glass melting tank , or more precisely the working tank in automated glass production .
task
The feeder is used to homogenize the glass, often assisted by agitators, and to set the glass temperature, which must be adhered to very precisely for a constant drop weight. The feeder machine attached to the end of the feeder forms drops of glass, which are then formed into the finished glass product in the processing machine.
functionality
The molten glass runs in the channel-like forehearths (channels) to the basin (also bowl ) of the feeder head . The channel is divided into several zones (usually 3 to 4), each of which has a temperature control circuit: in each zone the temperature is measured using a thermocouple or pyrometer and the heating or cooling is automatically set accordingly. The heating takes place either by means of gas burners, direct current passage through the melt or indirectly by means of electrical heating resistors . To cool the glass in a zone, the insulated cover of the feeder can be opened (cooling flaps), whereby the glass emits heat radiation upwards. In addition, cold air can be blown in through the gas burner.
The drip ring is attached to the bottom of the pool . This determines the diameter and the number (1 to 4) of the glass drops formed at the same time. The rotating tube , a tube made of refractory material that dips into the glass and rotates slowly, ensures that the glass is evenly distributed in the basin . The drop weight can be adjusted by adjusting the height of the rotating tube.
Below the feeder head, the glass flowing out of the drip ring is cut into drops by the water-cooled knives of the scissors and fed into the glass machine via a channel system . At the same time as the shears, one (or more) plungers move up and down in the rotary tube . The upward movement of the plunger constricts the glass strand. At this moment it is cut by the scissors at its thinnest point and thus the required glass mass is portioned in the form of a drop.
The plunger and knife are driven by the feeder machine , which has to run synchronously with the glass machine so that the gob enters the machine at the right moment.
A glass vat for container glass usually has two to four feeders and can produce up to 600 tons of glass per day.
More functions
The feeder can also be used to color the glass: in the case of feeder coloring , the contents of an entire melting tank are not colored, but the colorant in granulate form is only added in the feeder and distributed with refractory stirrers. The advantage of the feeder coloring is that it can be switched to other colors very quickly. By using feeder coloring, it is possible to produce a different color of glass on each production line of a melting tank. The disadvantage is the higher price of the color granulate, which is why feeder coloring is mainly used in cosmetic glass production.
literature
- Heinz G. Pfaender: Schott glass dictionary . 5th edition. MVG, 1997, ISBN 3-478-05240-8 .