LGK-40/63IGBT OPERATOR’S MANUAL
16
speed.
When the flame is short while the cutting speed is too fast, drag L increases, so
the vertical and horizontal blow force of the arc is formed, the vertical one helps to blow
away the molten metal, while the horizontal one makes the molten metal flow backward
along with incision bottom, this over-heated metal will melt parts of the bottom metal
again, then the burr is formed when they cool down and melt together.
The burr is caused by overheat bottom. When the cutting speed is too slow, but the
incision bottom is so over-heated that it melts, the liquid metal flows to bottom metal and
combines into one which makes the difficulty to blow away molten metal by air current,
and then the burr is formed.
The air current blow force is not enough. When cutting with plasma, the arc blow force
consists of the air current blow force and the arc electromagnetic force, the air current
blow force acts the main function. If the air current blow force is not strong enough, it
cannot ensure all the burr is flown away, then the burr is formed.
The measurement to eliminate burr
Ensure the centering between electrode and nozzle precisely, so that the compression of
the plasma arc is not damaged, the concentration of flame and cutting capacity can be
guaranteed.
Enough power to ensure the fluidity of molten metal, as well as increase the stability of
the cutting speed and operation. This makes it possible to adopt large air flux to enlarge
the air blow force, and beneficial for eliminating burr.
Adjust suitable air flux and cutting speed. If the air flux is too small, the blow force is not
enough, while if too big, the plasma arc will be shorten, the incision will be “V” shape, the
drag enlarge. The burr can be formed under both conditions. When cutting speed is too
slow, the incision is large and rough, the bottom is easy to be over-heated, while the
cutting speed is fast, the drag is enlarged, this is not beneficial for eliminating burr.
So under certain circumstance, there exists a proper selection range for air flux and cutting
speed.
Diminish the cutting surface slanting and rounding problem
The incision surface is a little slant and the upper side is a little round during cutting with
air plasma. Though the slanting range is acceptable during the cutting process, in order to
improve the cutting quality, people begins to pay attention to this problem. Usually slowing
down the cutting speed properly can avoid the slanting, but this may enlarge the effect zone
and incision width, as well as decrease the production capacity, so this measurement is not
wildly used. Recently, people can avoid the slanting by improving the nozzle structure, this is
called super cutting method. By adopting multi-hole nozzle during the cutting process, the
air current from the small hole is parallel with that from the main hole, this can avoid the
dispersing of the plasma flame on metal top, and then a parallel incision, square upper side
and no metal slag seam on the lower side is obtained.
Troubleshooting & repair
1.
If there is trouble caused by high voltage in the machine, a professional electrician or
serviceman of our company is required to repair it.
2.
Please check following first when there is trouble.
1) The three-phase power should be 380±40VAC
，
check if it misses phase or voltage fluctuation
exceeds its required range of power supply
；
2) Check if the supply abnormity indicator lamp is ON. If it is ON, check if the three-phase
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