Basic PLC Questions

I'm a mechanical engineering student. I am working on a senior design project. The project is to redesign a brazing machine. The current design is a partially automated system. I am looking a controlling a few motors. The motors would move a cart in and out. Also, I need to control how long the torches are burning. I want the machine operators to be able to push a button to move the part into the brazing system and be able to forget about it until it is done brazing. There would also have to be an emergency stop buton.

You guys are the experts here, I basically don't know anything about this stuff. Here are my questions:

How possible is this for a senior mechanical engineering student to figure this out?

Is this something easy that I could figure out when I get started, or will it take quite a while to figure it out?

Approximately how much would something like this cost?


Any help is very much appreciated.

Todd,

Feel free to register.

So it looks like you actually may have a simple operation.

Cart: presumeably a single axis Forward & Reverse

Torch: on & off (no flame adjustment?)How are you going to light the torch?

Does the torch head move also, or does the work move under a stationary torch head? What feeds the brazing rod? what about flux, or are we using an inert gas? Wire feed?

My guess is that you might be able to do it but first you have to lay down the process in better detail, if not for better responses, then for your better understanding of exactly what you have to do. Go ahead an layout the machine design then design the control system to fit the machine.

Mike got in before me...

I first, make a sequence of events, what happens, then what happens next.

From this, the logic can be programmed.

Click on Learn PLCs on the top of the page for more info.

Timers or counters could be configured to tell you your burn time. This could be on a display or digital readout.

A small plc could run $100-300. An Automation Direct DL06 plc has a snap on display, and probably has more capabilities then you need. With several pushbuttons, plc, display, etc, it will probably run $500-1500, depending how fancy you get. Below is a link to a picture of a small panel, in a 8x12 enclosure, that probably has more stuph then you need. Depending on the display unit, cost should be $800-1200.

Click here >>> "Neat Panel" picture. If page doesn't load well, picture is at post number 4.

Anyway, here's a start, and others will weigh in soon.

regards.....casey

ToddMEstudent said:

How possible is this for a senior mechanical engineering student to figure this out?

Click to expand...

Since you're a mechanical engineering student, I wouldn't expect you to get overly involved with designing the electrical end of this machine. This project might be better suited to be a joint effort between the mechanical AND electrical engineering students.

Don't get me wrong. A basic knowledge of the electrical end will be a big benefit to you. You'll remember to leave room for enclosures, wiring, sensors, etc., etc. when designing the mechanical end of a machine. Then you won't hear "Wow, Todd. Nice, compact design... Now, WHERE THE #%@& AM I GONNA RUN MY CABLES?!?!" from the controls guy...

Casey seems to have a 'thing' for that particular panel. To clarify, the connections to the outside world DID require another enclosure... :nodi:

[attachment]

beerchug

-Eric

I do like that panel.

Years ago we used the sloping panels for diesel engine auto-start panels for generators. 7 relays, one timer, two switches, and four lights. As I remember, 16" x 16" was pretty crowded.

What was the 8x12 used on??? Was wondering why you did not use a DL06, but the footprint probably was bigger.

regards.....casey

kc9ih said:

Was wondering why you did not use a DL06, but the footprint probably was bigger.

Click to expand...

Nope, it was because there was no such thing as a DL-06 (or even a DL-05) when this was built...

kc9ih said:

What was the 8x12 used on???

Click to expand...

I assume you mean what did the machine do? It was just a simple perfume bottle carton reader and accumulator. I have lots of pictures of this machine, but believe it or not, no 'overall' pictures. This was the best one I could find...

[attachment]

The cartons entered at the top of the picture, and got pushed one by one from infeed to discharge conveyor (In the picture that would be right to left). The pusher allowed a stationary barcode scanner to read the carton during the push, and also provided a way to control the flow of cartons to the discharge.

The cartons stacked up in the discharge conveyor, and once there were enough, a wide pusher moved the entire stack onto a deadplate (the pusher is fully extended in the photo). The bars you see on the deadplate are connected to chains at either end, and function as a really wide, but short, flighted indexing conveyor to accumulate 3 stacks. The operator packs each stack in a shipping carton, and a label containing that stack's barcode info is automatically printed for the shipping carton.

I just found my plan view of the machine, so I'll include that in a second post. It'll probably make more sense than the picture...

beerchug

-Eric

Here's the plan view as a PDF.

[attachment]

beerchug

-Eric

I would recommend you Call Automation Direct's Tech Support and have motor nameplate information available for drive sizing.

Also you will need a whole load of data to qualify your extimate. Do you need NEMA rated CB's or can you use iec contactors etc. What is the required IAC rating of fuses with respect to the feeder line.

Are the motors to simply stop when they hit a limit switch or run off an encoder and do positioning?

If you have absolutely NO experience in programming any touch screens (HMI's) or PLC's I would try to arrange an instruction course for your whole class with Doug Bell (Automation Direct guys will give you his number) maybe your school can subsidize.

In any event http://www.automationdirect.com

RE: cost if you went with that vendor you couldn't get it much cheaper anywhere else and the prices are right on the web-site.
I don't know how friendly they are to someone who has no intention of purchasing but as a potential future consumer they should be more than willing to educate you.

Have Automation Direct send you a catalog. Given enough time, you can get quite an education from it.

Visit "Learn PLCs" at the top of the page, quie an education there, too!

regards.....casey