Pin Installation Machine

rsdoran said:

You are doing something I would never do i.e. use a latching STOP button to power-on and start up. An ESTOP should never be used as a reset.

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Actually, there is separate hard-wired RESET button that has to be pushed to reset the MCR after the STOP button is unlatched. I made a mistake in not mirroring this logic in the PLC program.
I'm adding another contact block to the RESET button, wired to a PLC input X14, and adding a rung to the beginning of the program which should correct the problem:



Thanks very much for your input, Ron!

Paula

Lancie1 said:

I think my new timer T2 is still the best solution.

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I think it would make sense if the escapement was prone to missing cycles, and could be corrected by re-initiating the sequence. But this hasn't proven to be the case. It is always something upstream of the escapement mechanism. To date, there has not been a single problem with the pin-feed sequence (save for the present issue) where re-cycling the escapement would have corrected the problem. One time, a small metal chip got caught in the feeder track between the bowl and escapement, which prevented the pins from reaching the escapement. Another time, an operator had placed something heavy on the enclosure which covers the bowl. The weight actually bore down on the bowl, compressing the rubber mounts, and causing a misalignment between the discharge track and escapement inlet. But the most common reason that the pin-feed cycle "fails" is because they let the bowl run out of pins. The operators know as soon as they hear that hiss of air, with no pin being delivered, to shut down the machine and check the bowl.

Still, the repeating timer might be a good idea, except that in some instances it might exacerbate an existing problem. For example, if the escapement works perfectly, and delivers the pin to the air stream, but for some reason the pin hangs up between the escapement and nosepiece, the PLC will keep sending pins into the blow tube. Presumably, until it fills up with pins.

My plan for now is to try it out with the start-up rung as shown above. Hopefully this will solve the problem. Thanks for all your help, Lancie!

Paula

pstephens said:

But the most common reason that the pin-feed cycle "fails" is because they let the bowl run out of pins. The operators know as soon as they hear that hiss of air, with no pin being delivered, to shut down the machine and check the bowl.

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Why wait for the bowl to potentially empty?

Why not add a bowl level sensor or track level sensor far enough upstream so the operator can fill the bowl without an interrruption? You could initiate a "not-so-loud" audible alarm. Some of the Sonalerts by Mallory are chimes or other types of tones.

This was a low budget project that requires an operator to insert parts. The operator should be aware of the amount of pins in the bowl. Pictures are on Page 5.

What Ron said. The level switch was offered as an option, but they declined. The bowl doesn't run dry often enough to be a problem.

Paula

pstephens said:

What Ron said. The level switch was offered as an option, but they declined. It doesn't happen often enough to be a problem.

Paula

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I took Ron's advice and checked back at the pictures earlier in the thread. On a machine that small, the operator should be severely punished if he (or she) lets the bowl run out of parts! Sorry for the overkill suggestion. I'm too accustomed to huge machines with lots of sensors.

I probably should not have answered but heck I feel like I actually worked on that machine.

rsdoran said:

I feel like I actually worked on that machine.

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You did. (As did a few others!)

I downloaded the revised program to the PLC today, and the problem is solved.

MANY THANKS to those who offered advice! :site:

Paula

Paula, Where have you been the last 6 years?

Now lancie
She's too young for you.

I just wanted to know if she is another casualty, or has moved on to other pastures. Long-timers disappear from here, and I never know if they have passed on or what.