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Torch Height Control Process
« on: February 17, 2013, 08:10:09 AM »
Hi All

I tried searching for explanations in the simplest terms the process of THC and how it functions with software, thus hoping I can get a detailed yet simple explanation.
I'm pretty sure I'm not the only one in need of this understanding. I understand why it's necessary with regards to cut quality etc and saving the torch to some degree. But! What I don't understand is the actual process in which it operates and what is expected from an operator.

Here are my questions
1. Describe the arc ok signal and it's role? Does it play a role in torch ignition?
Terms like pilot arc, arc transfer and arc good - are there differences?

2. Why are some plasma models expected to have a current transformer? And are the connections different if current transformer is used?

3. THC Units requiring raw arc volts, compare to voltage divider?
4. The function of voltage divider (50:1 and so on) and differnce to raw arc volts?

5. What is expected from the operator with regards to settings/adjustments etc?
6. What is is the installer/fabricator/DIYer expected to know - if they (like myself) are electronically challenged?

It's fine to read connection diagrams, software config and hook up a product but having a bit more knowledge on the process would make it a lot more easier if we run into problems.

My final question
Advantage and Disadvantage comparison between Arc Voltage THC vs Mechanical THC? What is the real difference?


Feel free to add in explanations if I've left out vital questions.

Offline BR549

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Re: Torch Height Control Process
« Reply #1 on: February 17, 2013, 10:38:42 AM »
1. The arc ok just lets MAch3 that the arc is established and it is ok to start moving.

2. The ones that need a CT do NOT have access to the arc voltage so you use a CT to establish the arc voltage.

3. THE machines that ONLY have raw voltage requires a THC that DOES have  a voltage divider for step down voltage. Raw voltage would DESTROY a unit without a stepdown builtin.

4. The voltage divider simply steps DOWN the voltage level so the electronics wil not be destroyed by the high voltage from the plasma unit.

5. THE op HAS to understand the relationship of Set voltage VS feedrate to maintain the proper HEIGHT.  THE HEIGHT is the most important feature for proper cutting. Most manf give you the proper height to pierce and cut at. It is the OPS jog to maintain that height properly. You may need to go higher or lower on the arc voltage to maintain that relationship.

6. SEE #5 above AND you must know HOW the control software works to start and restart a cut.  A working knowledge of G code would be very helpfull.

7. NO difference IF everything works as it should and conditions are repeatable and the slag on top of the matr=erial is NOT a problem for the mechanical unit.

Hope that helps, (;-) TP
« Last Edit: February 17, 2013, 10:40:19 AM by BR549 »
Re: Torch Height Control Process
« Reply #2 on: February 17, 2013, 11:20:35 AM »
All well understood, except need clarity for the following...thx


"3. THE machines that ONLY have raw voltage requires a THC that DOES have  a voltage divider for step down voltage. Raw voltage would DESTROY a unit without a stepdown builtin."

So my understanding is the powermax 45 offers both options. And depending on the THC unit design it will require either connection. Would that be about right?


Offline stirling

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Re: Torch Height Control Process
« Reply #3 on: February 17, 2013, 12:13:16 PM »
So my understanding is the powermax 45 offers both options. And depending on the THC unit design it will require either connection. Would that be about right?
No - that is incorrect. The 45 (or any other plasma system) does NOT "offer" raw arc volts. Raw arc volts are present on the internal circuitry. Some THC's require an interface to be fitted internally to divide down this lethal voltage. Some other THC's  ;) connect to the purposely designed interface that is present on most Hypeertherm models including the 45 as standard and so do not require any internal work to be done on the plasma system.
« Last Edit: February 17, 2013, 01:26:49 PM by stirling »
Re: Torch Height Control Process
« Reply #4 on: February 17, 2013, 02:42:20 PM »
Thx stirling

Ok now I get it  ;)

I recall we chatted over email when I enquired about your thc unit. I will be ordering soon on my next build. My only concern being - which I'm experiencing now - is the second port needed. I can't seem to get a suitable wine that signals in Mach 3.

Your THC interfaces with the Cnc cable with powermax and don't require any interface connection to J21 and J18 for raw arc volts.

Offline BR549

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Re: Torch Height Control Process
« Reply #5 on: February 17, 2013, 02:59:45 PM »
YOU did install the driver for the 2nd LPT card correct??? 

(;-) TP
Re: Torch Height Control Process
« Reply #6 on: February 17, 2013, 03:10:12 PM »
Yep and uninstalled as well as reinstalled but still no luck.

Offline BR549

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Re: Torch Height Control Process
« Reply #7 on: February 17, 2013, 03:41:48 PM »
Next did you look up the address of the card in the Windows device manager ?  IT could be setup as anything not just the standard lpt2 port address.

(;-) TP
Re: Torch Height Control Process
« Reply #8 on: February 17, 2013, 04:27:58 PM »
Yep I've put in the correct hex address - even tried the second address. I noted when I change address - the green led's in diagnostics change and the torch up and other LEDs light as if in error.

I'm wondering if the port card is not shot because when I did this first time I had the wrong connection by supplier for torch and arc ok on thc. Perhaps might have caused a problem. Could it?
I purchased a second moschip card and tried but only the other day found the erroneous connection. Haven't replaced that card since.
Is it possible the input arc ok connection and the output torch connection swapped could have cause a problem?

Offline BR549

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Re: Torch Height Control Process
« Reply #9 on: February 17, 2013, 05:09:51 PM »
I would not think so.  When you had the LEDS  working did you toggle the functions on and off to see if the LEDS were toggling as well ?

(;-) TP