machine cycle time

hi all,

i'm sorry, but this is a little long winded.
i discovered today that someone years ago created a bunch of formulas incorrectly and it has left me in a bind. some how , some way they left off part of the sequence.

i am tracking the weld joint of a belt conveyor. the pusher system clamps the belt and pulls is from 3" to 18" based on the spacing of a prox switch located on each end of the stroke. the purpose of this is to turn on an alarm in the hmi application to signal the operator to inspect the weld joint.

since the line is based on inches per minute, i need to time the line for 60 seconds. what i am having trouble with is how to time the system for that period.

the cycle is clamp, move forward ands make a prox, dwell, unclamp, retract and make a prox, dwell and start over.

i have the logic down for everything and it works, but the inches per minute are not where they should be. the hmi displays 10" but we are actually moving 13.5" per minute.
i track the movement based on the cycle stroke which is 4.5" and is constantly checked for accuracy but changes based on product.

the problem is that when the belt speed changes, the pusher stroke time is automatically changed and the formula to figure the cycle time is off causing the number of cycles to be off.

this is a plc5 system and any suggestions as to how to approach the programming of the unit will be much appreciated.

thanks in advance,
james

since I posted this late last night, I am looking into using the prox switches to start a timing sequence and also use a counter.

any other suggestions or comments?

regards,
james

I don't think it is 100% clear what you are trying to do.

Are you looking to display the time the cycle is actually taking or do you need to control the time different parts of the cycle take?

The problem is that when the belt speed changes, the pusher stroke time is automatically changed, and the formula to figure the cycle time is off, causing the number of cycles to be off.

Click to expand...

Without knowing all the details, to fix this type of problem, the formula that figures the cycle time must have some adjustable parameters. These adjustable or variable parameters must be changed by the PLC program at the exact moment that the belt speed changes, in order to calculate the correct cycle time.

I am sure that is easier said, than done.

Android app for cycle time calculation

I have to deal with machine performances improvement everyday, I'm an automation engineer like many of you, so I developed a powerful tool for Android to get cycle time just tapping on a button, record every cycle time and export data. I hope you will find useful: https://play.google.com/store/apps/details?id=com.avafab.cycletime

avafab said:

I have to deal with machine performances improvement everyday, I'm an automation engineer like many of you, so I developed a powerful tool for Android to get cycle time just tapping on a button, record every cycle time and export data. I hope you will find useful: https://play.google.com/store/apps/details?id=com.avafab.cycletime

Click to expand...

That's a neat app. avafab.

Only slight criticism is the "Lap" button needs to be DOMINANT, I mean MUCH bigger.... Imagine trying to hit this button when you are watching the machine, not the android screen. There's a lot of screen space to play with, so it should be easy enough.

To determine cycle time:

1st Rung - just an RTO Timer. Set the Preset to a large number that you don't expect to ever reach.

2nd Rung - XIC (clamp output) + [one shot] then MOV the RTO.ACC to an Integer "Cycle Time". Parallel the MOV with a RES for the RTO timer (make sure RES is AFTER the MOV).

3d Rung - DIV 1/cycle time(scale to preferred units) to get cycle per time unit.

4th Rung - Mult the distance moved during that cycle by cycle per time unit to get distance per time unit.

Compress/expand into fewer/more rungs as desired

thanks everyone,

I see that my last posting failed to attach to this link.

I have completed the project and all is working great.


thanks again,
james

Cycle Time (stopwatch) app new features

daba said:

That's a neat app. avafab.

Only slight criticism is the "Lap" button needs to be DOMINANT, I mean MUCH bigger.... Imagine trying to hit this button when you are watching the machine, not the android screen. There's a lot of screen space to play with, so it should be easy enough.

Click to expand...

Hello, thank you for this feedback, in the next release (on February) you will be able to use volume buttons up/down to start/stop the timer, so you can avoid to look at the screen during measurement.

avafab said:

Hello, thank you for this feedback, in the next release (on February) you will be able to use volume buttons up/down to start/stop the timer, so you can avoid to look at the screen during measurement.

Click to expand...

Cool !