automatic drill machine, need advice

Hello,
I'm working on an automatic drilling machine. It's mostly a pneumatic system with a couple 120VAC coil solenoid valves controlling an air cylinder (loads parts to be drilled) and a Dumore pneumatic feed drill unit (drill motor is 110VAC 1/3HP). It's all controlled with timed relays now, built by an old employee.

I need to create a "peck drill" motion with the drill motors' pneumatic feed. The nature of the parts, depth of drilled hole, and lack of control of the pneumatic feed, creates long chips which bind up and break the drill prematurely. A peck drill motion (advance part way, quick retract, advance further, quick retract etc... like 5 times in one cycle) will allow the chips to break and be cleared from the tight fitting drill bushing, and let coolant in to cool the drill/part. This will improve things alot.

Ideally, a stepper/servo driven axis would replace the pneumatic feed. This would allow much better control of feedrate as well as even better control of the peck drill motion (IE. controlled by distance rather than time). I'm reserving this as an option if 'pulsing' the the solenoid valve doesn't work.

I've got other projects in the future, like cut to length machines, that will be good candidates for PLC control also, so I want to learn.

I've looked alot at Automation Directs' DLO5/DL06 PLC's. I figure the pulse (step/dir) outputs would come in handy if I decide to go with a stepper/servo based axis.

What other affordable micro or "brick" PLC's can anybody recommend? I've read about "progammable relays," and Entertron etc... This is more of a low budget setup, so high $ PLC's and programming software is out of the question. But I would like to learn a family of PLC's that enable me to grow into bigger more complex systems (motion control with servos is a special interest in my field of work), while not having to re-learn a totally different product and programming software. I guess I need AC outputs because of the 120VAC coil solenoid valves? Any advice would be appreciated. Thanks.

Depends how many I/O you require and whether you need high speed inputs or not.

Many of the Omron CPM series shoe box units have PWM outputs available. They also have interrupts etc.

Too much for programmable relays. I use them for cheap 4 channel (ro more) time clocks only these days. They do have a place in life though for many applications.

But I would like to learn a family of PLC's that enable me to grow into bigger more complex systems (motion control with servos is a special interest in my field of work), while not having to re-learn a totally different product and programming software.

Click to expand...

Omron CX-Programmer will program ALL current PLCs and will, with upgrades, program all future PLCs, except smart relays. The lates version has function block available and next versions will include all other IEC languages.

The next processor up I would consider is the CJ1. Processor types go from 156 I/O to 2096 I/O, all with varying scan speeds etc but all have the same function set. They all handle Omron Compo Bus S, (Omron inexpensive remote I/O system) and Device Net. By the way, one can place several Device Net scanners on the lowest function processor and have up to 64 Device Net I/O per Device Net scanner. You can far exceed the 156 I/O limit of the lowest end processor this way.

Many different types of motion control cards available for this PLC. Serial cards for communications with serial devices are inexpensive. Easily programmed with CX-Protocol. I can write a communication protocol for a strange device in about 1/2 hour and test it.

I guess I need AC outputs because of the 120VAC coil solenoid valves?

Click to expand...

Not really. You can use a transistor card to drive an external relay (DC relay with flywheel diodes). In fact, for pulsing a solenoid I would recommend this. Remember you are going to give the relay an absolute pounding. A lot easier to replace a relay than have to pull the PLC apart because a relay fails. You can also just about guarantee that it will happen in the middle of the night. I very rarely use relay output cards any more. Have not had a transistor card failure for about 4 years and the last one that failed on me had been incorectly wired. The relays had flywheel diodes in them, negative to positive, positive to negative and the transistors went bang in the night. Careless electrician, or did not understand the principles of transistor outputs and flyweel diode relays.

snaggletto,

I'm biased towards AD. If your only trying to control Z and not X & Y also a DO-05DD and a stepper control just may do the trick. For a small low speed application you may not need a counter module as the '05 has hi-speed outputs for driving the stepper control.

PLC: http://www.automationdirect.com/adc/Shopping/Catalog/PLC_Hardware/DirectLogic_05/PLC_Units/D0-05DD

Stepper stuff: http://www.automationdirect.com/adc/Shopping/Catalog/Stepper_Systems

Software is inexpensive: http://www.automationdirect.com/adc...ware/DirectLogic_05/Programming_SW_-a-_Cables

AD has lots of examples for programming for steppers, and the sofware is a quick learn. If you run into any trouble you'll get lots of help either on the AD forum, or on this one..

BTW if you need one or two AC outputs, just add a 24vdc relay.. http://www.automationdirect.com/adc...Timers/Electro-Mechanical_Card_Relays/RS4N-DE

Have fun.. Mike.

Thanks for the reply,

This particular application won't need much IO. I guess 2 outputs for the solenoids. As for inputs, I will need be using 3 limit switches for safety, and a 4 toggle switches for coolant, AC drill motor, and 2 manual overrides for parts feed and drill feed (useful during setup). These overrides don't need to go through the PLC however, they can be hardwired.

If I decide to use a stepper/servo driven axis, standard step/direction would be preferrable. Higher pulse rates mean faster feedrates. This won't be of much use on this machine, but would be nice for a cut to length machine in the future.

Elevmike,

From what I've seen, the AD PLC's look very attractive, and very obtainable. I would have no clue of where to buy AB, Omron other other brands.

About the 24VDC relay you mentioned, you mean to use the PLC's DC outputs to trigger a 24VDC coil relay switching 120VAC to the solenoids rather than buying a PLC with AC outputs and wiring the solenoids directly to the PLC?

About the AD PLC's. I'm wondering if it might be smarter for me to buy the DL205 programming software, rather than the DL05 software. As the DL205 software is backward compatible, and one day I might like to use a DL205.

What about Entertron PLC's with the free software. These look interesting too, but don't seem to have the features that the AD PLC's do.

snaggletto said:

.... the AD PLC's look very attractive, and very obtainable. I would have no clue of where to buy AB, Omron other other brands.

Click to expand...

That's one of the attractions. They also provide very good support.

snaggletto said:

About the 24VDC relay you mentioned, you mean to use the PLC's DC outputs to trigger a 24VDC coil relay switching 120VAC to the solenoids rather than buying a PLC with AC outputs and wiring the solenoids directly to the PLC?

Click to expand...

Yes.. this would allow you to use a combination of AC and DC devices that will be controled by the PLC; such as both a stepper and valve.

snaggletto said:

About the AD PLC's. I'm wondering if it might be smarter for me to buy the DL205 programming software, rather than the DL05 software. As the DL205 software is backward compatible, and one day I might like to use a DL205.

Click to expand...

Personally I would go for the $495.00 "full boat" version of DS4, but you said you were on a budget....

snaggletto said:

What about Entertron PLC's with the free software. These look interesting too, but don't seem to have the features that the AD PLC's do.

Click to expand...

I have nothing good or bad to say about Entertron. As a matter of fact I plan on buying one and playing with it latter this year. However we have a considerable investment in AD stuff..a few years ago I bought a couple of palates of AD stuff from a liquidator, and am still working from that stock. Additionally I know AD stuff pretty well and we're very comfortable with it.

snaggletto:

Is the feed strictly pneumatic or is there a "hydro-check" that lets you control the feed rate? This can help get a more consistant feed rate and thus would make any time based peck routine more consistant.

I once helped program a machine that was drilling 1/8" dia. holes almost 3" deep... That was around 30 or 40 pecks per hole. It was a stepper motor system with an ACME screw slide and a 4 spindle head on the slide.

I've also seen a completely mechanical pecking control. Very cool to watch but would wear our rather quickly by todays standards.

What's your 3rd limit switch for? I'm thinking home switch, and done switch (i.e. part drilled). Where does the last switch come in? Perhaps an end of stroke?

I have done a couple of small drilling machines, but have not had to pulse them. I would think that a plc clock pulse (actually several of them) could be used to pulse the drill down to the desired position, or through the piece being drilled. I normally use relay output for the higher current rating.

Bob has a preference for Omron, but I prefer other brands. I did turn down an offer for an interview with their tech support department last summer, they make a product that is good for many applications.

As mentioned, you need to know how many I/O you need. There are several PLC's to choose from. Some come with FREE software, others you have to pay for. Here is a short list of several, you can find links for most of them in the Learn PLC's at the top of the page, then schroll down to Manufacturers Links. Many manufacturers have "Starter Kits" or "Tool Box" kits, which include software and a programming cable, at a special price. No doubt, some others will probably add some choices, too!

Allen Bradley, ML1000, 4 triac outputs, $99, download free software.

Moeller "easy" relay (and several other brands), 4-12 I/4-8 O, expandable, some with built in software, or download Allen Bradley PicoSoft. $119 and up.

GE Fanuc, VersaMax Micro and Nano, several configurations available, Tool Box Kits available.

EZ PLC, new, cheap, different, no one reports using one yet. Maybe TOO new!

Automation Direct, you appear to be familiar with them, already.

The PLC that I currently have on hand is an Entertron. It is a circuit board type PLC, as opposed to a brick. Software and Tech Support are FREE. They are purchased direct from the manufacturer. Program can be wrote and run on computer, without a PLC, for true simulation. Entertron units have higher output ratings then most other PLC's, and a longer warranty. This particular model has 7 amp contacts! They are competetive price wise, too. Their smaller plc's are 6 In/6 Out up to 12 In/12 Out, with larger units available. I have several programs including diesel auto-start controls, drill and boring controls, pump panels, inverter bypass, a cap tightener, a multi-stage clamp, a couple of small conveyors, and several flashing light signs. I have found entertron to be very cost effective.here is a "LINK" to their small unit.

Take some time, take some notes, feel free to post a lot of questions.

best regards.....casey

just a suggestion. if you are simply wanting to eliminate long spirals entangling your tools and breaking them, have you tried just changing the "pitch" or cutting angle of the bits? we did this on a machine we use for drilling s/s bedplates up to 2" thick, with good success. just a thought.

danatech

danatech said:

just a suggestion. if you are simply wanting to eliminate long spirals entangling your tools and breaking them, have you tried just changing the "pitch" or cutting angle of the bits? we did this on a machine we use for drilling s/s bedplates up to 2" thick, with good success. just a thought.

danatech

Click to expand...

Changing tool geometry may help.

You can also make yourself a crude linear encoder by using a piece of rack (as in rack and pinion) an a small prox reading the teeth. Be sure to mount it sideways so chips don't build up in it.

This along with a hydra-check would give you pretty good results. The only problem is cycle time. With a servo, you can rapid back to where you left off. With the pnematic system, you will go back into feed at the same place always.

Elevmike,
I'm definitely sold on AD, I've been drooling over their catalog for over 6 months. I will give them a try in the near future, whether I go with them now or not.

What benefits would I gain by going with the "full boat" version over the ~$199 DL205 version? More instructions? I doubt to ever use anything more powerful than the DL205, in AD products.

Ndzied1,

No this model is only pneumatic unfortunately. I got quotes last week for pneumatic/hydraulic models from different companies. This does enable much finer control of speed, which I need. Most also offer a "peck" or "pause" mechanics, but still require "extra electronics" to pulse the solenoid. Bottom line is that they cost $3000 - $3500, without "extra electronics." This might very well solve my problems, or it might not. I figure I can buy a PLC, and single axis stepper/servo system (if needed, pulsing the air cylinder may do the trick) for around the same $ or less. However, at the same time, I will have learned about using PLC's, which will be invaluable for future automation projects I have in store me.

There is currently only one limit switch that is triggered by the parts feeder. IE. don't feed the drill, until a part is loaded into the fixture. I thought I might need a LS to signal when the drill is through the hole, and when drill is fully retracted after drilling the hole, to signal the parts feeder to back off/get another part/start over. The current machine does this only by relay timer. If something gets hung up or slows down for some reason, it will get "out of time."

Kc9ih,

I will definitely shop around some more. A smart relay would do the job of pulsing the solenoid. However, it won't drive a stepper/servo I don't think. I really need this feature as a back up. Entertron really looks good to me too, I'll research them a bit more.

Danatech,

You make a great point. In reality this problem is a machining problem and NOT really a control problem. However, the current control is pretty weak, no safety features, unreliable, jimmy rigged and needs work either way. Also, I'm just looking for an excuse to get my feet wet with PLC's

The machine worked fine at one time, when these parts were made on a screw machine. However, we've since changed to 'heading' them. Using a cold forming machine, cold header, progressive bolt maker, different names for the same type of machine. Basically it take a 2-4K lb. roll of wire (1008/1022 mild steel), up to 1/2" diameter! Feeds it in, cuts it off and hammers it into multiple progressive dies which forms a larger diameter head on one end out of the smaller wire size. It makes about 1.25 parts per second! The parts come out smoking, literally. Needless to say the heads are work hardened. Now the material is a PIA to drill. I will be trying different type drills, but the current drill feed motion is far from ideal.

M91, anyone?

Have a look at this:

http://www.unitronics.com/pdf/m90_91/m91-2-t1.pdf

The unit has a 10 Khz HSI and 2 Khz HSO. Also, a two-line display for anything you might like to input/output to the operators (counts, speed settings and such). It has a single serial port that can be set to RS232 or RS485, modbus compatible, with 12 inputs and 12 outputs (all pnp).

Software is free, so download it and see what you think. The last price I had on the unit was $339 US.

TM

snaggletto,

I have been reading your post, regarding your search for a PLC for your application. By way of introduction, my name is Stephen Luft and am employed by Entertron.

Based on what you are looking to do, the Smart-PAK series would be sufficient. Depending on if you go servo or stepper, we do offer analog I/O and PWM output capabilities.

You can download our software from our home page. It is password protected, so you will need to complete this form - www.entertron.com/form.htm and a password will be sent to you.

You can contact us directly to further review your application...I will also forward this thread to one of our techs. to review.

FYI - the software you download is for all of our products, so you don't have to worry about only having software for one family of products.

snaggletto,

Would you be able to use a few limit switches to do the pecking ? BAsically the first limit switch will make it retract then it will go on to the next limit switch.....and so on until the done limit switch is activated. Also on another note, is your product your going to be drilling going to change (thickness) or is it always going to be the same ?

David

The 205 version of the software ONLY does the 205, not everything up to the 205. If you want to cover all bases then the full PGMSW package at $495 would be the ticket. The family limited software versions are not upgradable to the full package. Each family has benefits.