New to PLC's and am trying to build a packing machine

wynsel · Jun 21, 2009

Hi, I'm new to PLC's and need some input on them. I'm building a packing machine that runs a vibratory feed that feeds a scaled hopper. the scale controllers out their will work with gust one line. but I would like to run three lines simultaneously and the scale controllers can not do this. they say i need a PLC to accomplish this. but how does the PLC read a load cell to stop the vibratory feeder when it hits it's target weight??? is this a counter up bit?????????

realolman · Jun 21, 2009

wynsel said:
Hi, I'm new to PLC's and need some input on them. I'm building a packing machine that runs a vibratory feed that feeds a scaled hopper. the scale controllers out their will work with gust one line. but I would like to run three lines simultaneously and the scale controllers can not do this. they say i need a PLC to accomplish this. but how does the PLC read a load cell to stop the vibratory feeder when it hits it's target weight??? is this a counter up bit?????????

There are companies that make cards that go in a PLC slot that do this. We have them where I work. If I can get over this brain ****, I will tell you the name of them. Maybe you could google something and come up with it.

Mickey · Jun 21, 2009

What is the output of your load cell? If analog most PLC's will accept analog inputs. Once this analog value is in the PLC it can then be compared to the target value with compare instructions. The results of this compare can then be used to turn-on or turn-off an output, whatever the case may be for your process.

Stationmaster · Jun 21, 2009

wynsel said:
Hi, I'm new to PLC's and need some input on them. I'm building a packing machine that runs a vibratory feed that feeds a scaled hopper. the scale controllers out their will work with gust one line. but I would like to run three lines simultaneously and the scale controllers can not do this. they say i need a PLC to accomplish this. but how does the PLC read a load cell to stop the vibratory feeder when it hits it's target weight??? is this a counter up bit?????????

Wynsel,

Mickey's approach is right on. I've done exactly that. I'm not sure about the special purpose cards mentioned for this situation, but if your sensors work on "analog", you can just do it that way.

Have you selected a PLC yet? What PART of Florida are you in?

Stationmaster

wynsel · Jun 21, 2009

I do believe that it is analog. but the rep from flex weight did say I may need a card to place go in between the plc and load cell.I'll have to look more in to this..

I was looking at a Dayton from grainger but not sold on it yet..

I am located in the Tampa area..

Kev77 · Jun 21, 2009

It sounds like the scale is a package unit. If you are just using the load cells then there are converters out there that can convert to 4-20ma. I have seen several setups in Powell Fillers. If you are going to program this, keep in mind that there is more to getting a weight then just using a compare instruction. The ones that I set up before would use a dribble function. For example:

Target: 20 lbs.
Filler will run up to 18lbs., pause and run in 1 second bursts until the target is met. We also used a gate at the end of the pan that would close after the bulk fill and only allow a small amount of product to go into a box. It all depends on how accurate you want to be.

Here is a link to a filler that I have worked with: http://www.powellsystems.com/awc.html

This filler has two scales and 4 pans. They work very well.

Kevin

realolman · Jun 21, 2009

I finally recovered from my brain flatulence...

Here is a link for some analog loadcell cards that will fit right in an AB PLC.

http://www.hardyinstruments.com/process_weighing/plc+plug-in+modules/

I don't know what you're trying to do, or what kind of speeds or accuracy you're looking for, but there are some fine packaging machines already out there for many years that achieve some very high speeds at some very high accuracies. Like way over 100 packages per minute at less than .5 gram error per package. You might want to see who you're competing against.

http://www.heatandcontrol.com/eqmain.asp?eqid=28

http://www.yamatoscale.com/

There's more to the subject than you might think. It ain't as easy as it looks.

wynsel · Jun 21, 2009

Kev77 said:
It sounds like the scale is a package unit. If you are just using the load cells then there are converters out there that can convert to 4-20ma. I have seen several setups in Powell Fillers. If you are going to program this, keep in mind that there is more to getting a weight then just using a compare instruction. The ones that I set up before would use a dribble function. For example:

Target: 20 lbs.
Filler will run up to 18lbs., pause and run in 1 second bursts until the target is met. We also used a gate at the end of the pan that would close after the bulk fill and only allow a small amount of product to go into a box. It all depends on how accurate you want to be.

Here is a link to a filler that I have worked with: http://www.powellsystems.com/awc.html

This filler has two scales and 4 pans. They work very well.

Kevin

Thanks Kevin,
You are very very close.. but on a much smaller scale of a machine.. we need to weigh in grams. like 145 to 185 grams..

There are machines out their in the six to nine head units. but they will not cater to the small guy..

As far as the logistics of building on!!! it is what makes me live!!!

Thanks realolman,
For the info on the load cell cards!!!!

wynsel · Jun 21, 2009

This is a single line machine!!!!

Kev77 · Jun 23, 2009

Sounds like a fun project. I once made a small batch ink mixer because nobody made one the size I needed. You could do use a small vibratory pan and conrtoller. It has analog control witch you could drive with a PLC to achive your target weight. One scale that I used before had the bulk and dribble setting built in and it closed seperate contacts that I used to trigger different speeds to a Eriez Pan.It was very accurate.

Here is a link for pans that I have used for a cookie dough filler;

http://en-us.eriez.com/Products/VibratoryFeedersAndConveyors/?gclid=CMazoYTEoJsCFRMUagodknbgBw

Eriez has good application support and can point you in the right direction.

Kevin

SteinCollector · Jun 26, 2009

I am the PLC product manager for Bosch Rexroth Corporation and we are one of the market leaders in the packing industry www.boschrexroth-us.com. We scale from small machines up to large ones. Drop me an email if you are interested in talking further. We have a large distributor right there in Tampa

wynsel · Jun 27, 2009

Thanks,
Sorry for not replying sooner, But I had to Chase redfish around the skyway for the last week.

Kevin, I've looked into eriez and are my second chose to martin vibration systems. It has a pneumatic drive system that is controlled by a 12v solenoid. I like this for all other operations of the system is all so 12v solenoids and pnumatic.

SteinCollector,
Thanks,
I'll drop you a email!!!

New to PLC's and am trying to build a packing machine

wynsel

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