Automated Loading and Ejection of boards

[hermygator]

Hello from the heat and humidity of the Midwest

I was deciding on our off season shop project. And have decided on automating the loading and ejection of boards into the bot. Here are my thoughts and the environmental parameters in which we operate. I would appreciate any thoughts ya’ll may have.
The bot
48x96 PRT, 2 PC routers, prox switches, etc. etc.
No vacuum hold down
Wood and Process
20,000-30,000 pcs from 48"x 5" x 5/8" cedar boards
At the moment what we do is rout the product in the cedar board leaving a thin
1/16 skin. As the program cycles the board is replaced and the process begins again.
The board is then flipped and ran through a drum sander and the parts are released. They then go to finishing where a slight round over is applied by hand using an inverted router. Ran through another sander and we are done.
All the work is done at one open end of the router. It seldom travels 18" down the x axis. We use the entire Y axis. The current hold down is physical. 2 threaded rods with plastic shoes and sand paper grips are turned until shoes touch board and board touches stops and board is “squeezed”. This creates a firm hold for the routers to “do their business”

Now what I have in my mind is a board hopper at the other end of the table that will hold say 30 boards. As the machine cycles pneumatic cylinders push a new board from the base of the hopper into the line. (NOTE imagine 5 inch boards laid edge to edge your entire x axis) Then the pressure is transferred down all the boards creating a hold against a plastic stop that is pneumatically controlled for registration and ejection.
Now the tough stuff for me is the relays, switches and outputs. I would like all of this controlled through the program file. The timing is important and ought to be computer controlled. I have many custom machines that I have devised that use many pneumatic physical switches I WANT TO STAY AWAY FROM THESE they are just not reliable enough for the shopbot
Control list
2 air Hopper cylinders working in unison( I see horizontal movement)
2 Stop Pegs, Bar or something on the opposite end working from the underside using 2 air cylinders.( I see vertical movement also in unison)
Sensor when hopper is empty Routers shut off.

All I have is a the control box a 12v hook up for a relay and a m5amp hook up. Do I have the plugins to control the timing of 4 systems including the 2 router shut off.

Ok guys put on your automation and mass production hats and point me in the right direction.

Thanks
Herm

[richards]

If I were doing the project, I would build a process control computer that would be basically independent of the Shopbot. However, I would use one output going from the Shopbot to an input on the process control computer to signal the process control computer to start the board positioning cycle. I would use one input on the Shopbot, coming from an output on the process control computer, that would be activated by the the process control computer when it had finished positioning the new board, thus signaling the Shopbot that it could run the cutting routine.

[richards]

Maybe I should have added a few recommendations about the actual process control computer. Z-World makes many small process control computers and microcontrollers priced from less than $50 to several hundred dollars. Their BL2100 'Smartcat' development kit (including an excellent Dynamic C programming language - required to develop programs) costs a little more than $400. Just the base model BL2100 card, for future projects, costs about $200. That particular model has easy to use screw in terminals for I/O connection. The Z-World controllers have built in timers, interrupts, TCP/IP (on the non-base models), and analog I/O (on the non-base models). Using their Dynamic C, you can program a state-control program in a matter of minutes.

To actually interface a process control computer to the real world, I use Opto-22 products. They have the G4 series of I/O modules that easily convert various voltages to TTL logic levels that are compatible with computers. The G4 modules plug directly into one of their 'racks'. The various racks hold anywhere from four to twenty-four modules each. Modules are usually in the $15-$25 range. The racks range in price from about $25 to slightly more than $100.

Adding pnematic valves and cylinders to the equation is simply a matter of buying the correct Opto-22 G4 output module to control the valve and then plugging in air for the cylinder and voltage for the valve (12VDC - 48VDC or 120-240VAC, depending on your preference).

One word of caution about working with solid-state-relays: Be sure to turn off all power before servicing any module. Even though the computer has turned a module off, SSRs often 'leak' enough electricity to give you a surprise shock. As far as I know, all SSRs from all manufacturers exhibit leakage.

[hermygator]

I thought a pseudo-independent computer control system may be required. I'm still looking at a couple of other ideas but I think that building this ol' girl will be a kick. Thanks for the information on getting me started.
Wade

[ron brown]

There is an old saying "It's not my cow" but, whay aren't you pallet loading the parts. In pallet loading a sub-board is loaded with parts and changed - In your case maybe 8 boards at a time. A second "pallet" is loaded and unloaded as the first one is processed. The pallet has clamps, vacuum chanels or fixtures to hold the work as necessary.

Properly designed a good pallet system will process a lot of parts in a day.

Ron

[oddcoach]

you said your parts are only 18 in long.
why not run 3 or 4 setups all the way across the table. you should have enought time to unload and setup while the router is cutting another setup.
to do your air cylinder setup could get expensive if you are going to get a bunch of 18 to 20 inch cylinders.
john

[hermygator]

Pallet system may work...If the desired operator-machine rythm can be found. The operator is releasing parts through the sander and putting the round over on as the router cycles. Board loading and unloading breaks up the rythm. Now would pallet loading do the same???hmmmmm
I nixed the set ups across the table for safety reasons plus well its just plain hard while 2 routers are screaming at ya. Thanks for the ideas now I will just sit and thinks

[dvanr]

Try EBAY , PLC starter kit , to load and unload your table it may be all you need.

[jhicks]

No input on loader recommendations but I was curious why you would unload and then process round over as a secondary hand operation? I had been producing several thousands of a long oval shapes in baltic birch and used a 1/2" roundover with a 1/4" cutter in the center.
Technically you could cut 2 opposing sides of two parallel pieces in one pass if laid out to use that cut path for both sides of the roundover bit.
You can order standard or custom combination roundover with a center flush cutter. With a roundover at your finish thickness dimension, cut through the material down to your 1/16" skin and deliver the required 1/4" or whatever round over you need in the same cutting process. The roundover stops at the top or slightly above the material as it hits the lowest Z cut dimension.
Loading sounds like a nice project to increase throughput but assuming you fully load the table and unload it more rapidly, you'll need 3 or 4 router tables and helpers to keep up with the edge finishing.
Several places will cut custom bits and they aren't as costly as one might think. Sounds like you have the volume to justify it. Best of luck.

[hermygator]

Jerry but then it would be a vacuum hold down on an island right???? We used to do a top pass that drilled indexing holes so when we flipped the board the next process had registration by using indexing pins. WAY TO SLOW to much non cutting movement. A Good finisher could easily keep up. If what you suggest doesn't need a vacuum then I must not be following. P.S. where are these custom bit places? I always just bought off the shelf and adjusted from there. If I could do a round over and leave my 1/16th skin in one pass. Holy Moly we would be cooking. HELP I can't see the forest for all the trees.
-----> feeling silly I never thought of that.

[jhicks]

Wade,Glad the idea opened a new line of thinking for you. You are correct that hold down issues exist but isn't that the purpose of your 1/16" skin anyway? Seems to me that throughput is your objective but you are only loading part of the table and trying to increase capacity from the loading aspect. Surely cant hurt but if you only run 1 stick at a time, there are several areas left in your space and time. From the little I know about your project, I would consider a couple wood rails/tracks along the X to capture the 48x5x3/4" raw stock lengths in rows that would allow for a progressive row to row linear run along the X, include round over as discussed. Should be able to slide in at least 7 to 8 rows on a 48" Y axis and 2 on the X.
Then move up the y to the next fixture/row progressively covering the stock and entire table in a single part file. Once one piece/row or 2 are cut, remove and replace with new stock and return to the beginning after row 7. Simple wing type wood clamps can be pivoted in the "rails" to swing open and closed as well. SAFETY FIRST AS ALWAYS!
Bit makers include Magnate 800-827-2316, Eagle in Ohio and others are out there. Sometimes they don't advertise customs but are waiting for you to ask. With your volume it should be easy to justify multiples.
Sorry for the long post but there are several techniques we have used and would be happy to discuss. E-mail or call and I would be happy to share our experiences and better understand what your trying to do to see if we could help. I believe there are several alternatives to increase throughput and eliminate secondary process before working through material placement. When every other aspect is optomized, movement on and off is a bonus but I think you will be able to keep busy with reloads and unloads and stay at pace with the machine in other less sophisticated ways.