Notes

Flashlight Height Control Via Arc Voltage Sensing for Plasma Cutting
The role of the torch height command system for mechanized cutting systems is definitely often understated. A good THC (Torch Height Control) is completely critical to get good cut good quality. It is a known simple fact that definitely typically the best possible control method is by realizing the cutting voltage. The cutting volts is directly proportionate for the height involving the torch and even the workpiece; better the distance, higher the voltage and vice-versa. So one particular can easily consider the cutting voltage as a command parameter and make use of the same with regard to controlling the stand-off distance. This method of control is frequently known as AVC (arc voltage sensing). Sensing the arch voltage is not lacking of challenges. The particular torch is exposed to a high regularity pilot arc, which usually creates plasma. This specific HF can easily traverse to typically the sensitive voltage testing circuitry and damage/cause malfunctioning with the method. It is absolutely essential to isolate the particular measuring circuitry from the plasma HF but be able to be able to measure the ac electricity accurately. Highly delicate arc voltage command circuitry can identify voltage variations below 0. 5V. Correct measurements as well as isolation can easily be achieved by means of use of Hall receptors.
Piercing through solid metals has the adverse effect on typically the life of the torch consumables. Therefore, piercing needs in order to be carefully managed in order to maximize the life regarding consumables. An appropriate spear like sequence is described below with schematics:
I) Every time a command is received by the CNC to get started on cutting, the flashlight height controller steps the torch into touch the workpiece, to ascertain absolutely no level. The dish can be sensed through multiple systems, most commonly applied is ohmic sensing / motor torque sensing / the combination of the two. When the plate offers been sensed, typically the torch now goes upwards.
ii) Typically the torch continually maneuver upwards to some programmed piercing height. About reaching this elevation, the plasma arc strikes along with the platter begins to obtain pierced While spear like takes place, the lot of smelted metal (depending for the thickness of typically the plate being pierced) jumps out associated with the plate plus forms a pool. The torch should be protected from this particular molten metal, therefore the torch carries on to move upward to a designed "molten pool jump" height.
iii) Typically the torch now actions downwards to the particular programmed cutting level. The THC unit now provides transmission to the COMPUTER NUMERICAL CONTROL to start movement
Plasma Torch
iv) The torch now continues to move additionally reducing height. Arc voltage is constantly given back to typically the control unit, which usually maintains a constant arch voltage through a great appropriate PID handle loop.
The above discourse amply demonstrates typically the role of your excellent THC for the great cut with sang.

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