Faster ,or slower for the tracking cutting status of Wire cutting ,either of which will have an influence on the cutting speed ,surface roughness of workpieces and processing stability .
Under the circumstance of the same high power and processing material , sometimes the surface of finished workpieces are clear and bright ,very delicate, still other time black and rough . This is because spark discharge must produce in a certain discharge gap, spark discharge can’t produce in the state of short circuit at both ends or no-load current ,moreover, the gap is slightly larger or smaller , either of which will have an influence on pulse utilization ratio of discharge efficiency . Hence, an optimal value exists .
Seek for the tracking optimal position of frequency conversion by the following means :
1)A reasonable match is made between pulse width and interveinal of high frequency power .( The rate for rectangular pulse generally requests is 1:4 between pulse width and interveinal ) .
2)Wire feeding is on after workpieces are clamped, start working fluid and high frequency power, firstly make workpieces and electrode wire in momentary short circuit and check the short circuit current , the ratio between normal working current and short circuit current is 80% more or less ,then start running ,modulate frequency conversion knob ,make the pointer on analog ammeter stable at 80% nearby in short circuit . The short circuit is 4A if workpieces in 50mm thickness is machined, so normal cutting current should be 3.2A more or less .
3)If the pointer on analog ammeter is found to sway below from time to time in the process of cutting ,it means that tracking speed is so slow that it needs to speed up the tracking . If the pointer on analog ammeter is found to sway above from time to time ,it means that tracking speed is so fast that slow tracking speed needs adjusting . If the pointer on analog ammeter is found to wag from side to side largely ,it means that processing is not very stable ,stop the machine and check the reason ,or wire is easily broken .
4 )The main reason for the pointer on analog ammeter wags from side to side as follows :① improper adjustment from pulse power parameter , little power to cut ,discharge energy needs increasing . ②the stability of wire feeding system is weak ,such as,the serious abrasion of the guide wheel ,bearing ,electrode block, the swing of wire electrode leads to unstable processing ,guide wheel and bearing need changing, conductive block position need adjusting .③abnormal working fluid supply ,water supply shortage for upper and low nozzle , or something wrong with detergency of working fluid in itself, water supply needs regulating or change working fluid ,of this situation usually happens when working fluid is discharged from nozzle ,but electrode wire can not be wrapped stably .
