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Greetings-

I was wondering if anyone has used a V-350 or other OPLC for a simple cut to length. Looking for programming ideas. The system works like this:

Operator sets the length of material he wants on the HMI

Presses start

Line runs until the preset

Line stops.

Operator cuts material by hand.

Particulars:

Existing Red Lion Mag pickup LMPC0000 which is sensed by a special geared sprocket. This displays on a Red Lion display unit to give the operator a Feet Per Minute rate display.

The readings on a FLUKE SCOPE METER are approximately 77 Hz. at a rate of 40 FPM.

My thoughts were to bring the mag pickup input into the high speed counter input I-0 and then scale the Hz to equal one linear foot. Take that value to a constant for a counter, then have a data entry register on the HMI for the purpose of the operator entering the desired feet he wants. This value would then be the preset for a counter for the stop command. The counter would have to be reset for the next cycle. We will have an output which energizes an IPR (InterPosing Relay) set up for normally closed contacts which will be in series with the existing line stop (not the e-stop).

I'm not sure just yet how to approach the ladder logic and math with the Unitronics. This is my first Unitronics OPLC. This is a proto-type for several more.

The machine is a stainless steel slitter- that is, they take one roll of 2 to 3 feet wide material and slit 1/2" to 4" strips which are wound up after the slitting. It is a continuous run until the desired footage is reached for the order. The purpose of the V-350 is so the operator can do other things while the machine runs, without the worry of slitting too much material. The plant wants to err on the plus side, that is give the customer more material as opposed to shorting an order.

Any ideas on how you might approach this would be appreciated.

Kind Regards,

B'rone

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  • MVP 2023

Have you asked your friendly distributor for assistance?

Read the Help on Math blocks and Compare blocks. The high-speed counter is mapped to an integer (I'd recommend an ML). After you do your math to get pulses per foot, run that result into a >= compare block and tie your stop output to that. Have an external start button wired to an input to start the process, and Store a 0 to the HSC register on a positive transition of when that's pressed.

Take a swing at the logic and post your code. We can offer suggestions from there.

Joe T.

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  • 3 weeks later...

Joe- sorry for the delay in responding. I got slammed... You wrote:

*******

Have you asked your friendly distributor for assistance?

*******

Yes. Before I made the decision to purchase the Unitronics brand and model for this application I made sure there was a distributor in California and I contacted them to make sure they could and would help me with the application. To date, now that I have purchased the unit, I have gotten no replies to emails or phone call messages. So that is why I posted here.

*******

Read the Help on Math blocks and Compare blocks. The high-speed counter is mapped to an integer (I'd recommend an ML). After you do your math to get pulses per foot, run that result into a >= compare block and tie your stop output to that. Have an external start button wired to an input to start the process, and Store a 0 to the HSC register on a positive transition of when that's pressed.

Take a swing at the logic and post your code. We can offer suggestions from there.

*******

That is my plan.

Thanks for the reply.

B'rone

*******

Joe T.

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linxchas- thanks for your reply... You wrote:

*******

<-Operator cuts material by hand.> ??

*******

This is a slitter machine. The operator places a master reel of stainless steel sheet on the payoff reel and feeds it through several knives which slit the metal to a width that the customer requests. There may be 4, 5, 6 or more take up reels for the order. The material cannot be cut with a flying cut type system, it could cause serious injury. As it is the operator has to be very careful when cutting it manually. It is not like cutting pieces for specific parts. This material is supplied to other plants, like Toyota, for making small parts, like the membrane push buttons which have a little click to them (switches) and the like. This company provides reels of large quantity for the manufacturing plants who then make the smaller cuts.

*******

Think about not to stop the machine, but use a flying shear

Here is a video for a similar machine:

In this case simple high speed encoder + V-350 is a perfect solution + full automation

*******

Again, this is a simple operation- operator enters the footage, presses start, machine stops when footage is reached, operator cuts then reloads with another order, different thicknesses, widths, lengths, etc. We opted for the HMI to replace existing Durant and Red Lion units. The Durant unit uses a wheel encoder which is driven by the sheet metal. Of course there is slippage and it is not completely accurate.

The Red Lion unit is a Feet Per Minute display and gets its' signal from a magnetic pickup which senses a gear (sprocket) made for the purpose and there is no slip because it is directly driven from the main gear box for the machine which is driven by a D.C. drive.

We are going to use the Red Lion LMPC000 magnetic pickup to feed a signal to the Unitronics V350-35-TR20 and display FPM as well as use a counter to calculate the accumulate feet for the purpose of opening an output which is in series with the existing machine stop. The machine is started with the existing real world start button. Only one output on the V350 will be used- for the stop circuit- NOT the E-Stop, but the machine stop. The HMI is to provide a FPM display, a preset entry pop up keypad, accumulated display and a cycle complete annunciation. Real simple in theory.

I have to take the FPM and convert the rate to actual feet per pulse in order to reach the setpoint entered by the operator, then stop the machine.

What I have so far is:

40 FPM=77 Hz

40 FPM=(77Hz x 60 sec)=4620 ppm

40/4620=.0086580

4620/40=115.5=1 foot

Convoluted perhaps...

I'm going to have to do some reading to figure out which blocks to use and how...

This is my first Unitronics project.

Kind Regards,

B'rone

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I have done this in the past for wire crimping machines and what has worked is as folllows:

1) I know how many pulses there will be for one revolution of the gearset and that is preset in my program. If you will have different gearsets with different numbers of teeth then you will need a customer enteerable parameter to have this be correct all the time (in my case I used a rotary encoder instaed of a mag pickup so the teak count is unimportant).

2) I programmed in the ability to make a singe rotation feed of the wire material and then require the operator to measure the length of material that was pushed out. The operator then enters this data and I then make the calculation for (length/pulses per revolution) = length per pulse.

3) Then I correlate the length of product operator wants (that they enter in) to pulses and then make a compare that when Pulses are greater than or equal to required pulses to meet length stop feed.

4) After stop I cut material

5) After cut I reset pulse counter to 0 and start all over again

6) user can enter in how many pieces they want then I have a second count for that.

Notes: We are talking about heavy material that will not stopinstantly so unless you have a cutting blade that will travel with material to make the cut you will most likely need an offset to of say (length in pulses needed - 3 pulses) = actual pulses wanted to end up at the correct length.

Keith

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