Industrial project feasibility assessment. Not a do my work for me post: lookin
Phils88gt
Posts: 2
Everyone,
·· It’s a pleasure to finally have the time to post here, and perhaps retrieve a feasibility verdict based on the vast experience I assume lies in this forum. I obviously am seeking help, but I would like to at least offer the façade that I am not helpless. ·I’m a machinist, cnc programmer, and cad operator by day. I have some electronics background, and am definitely confident of my mechanical aptitude. I purchased a BS2 to learn how to program such a device for general application. My job does not require it, but I think I can apply a programmable PLC to my work.
·
·
Reason for constructing device:
·
··········· I wish to create a device which will remove a mundane task from the hands of a worker whom I deem his skills too great. A task repeatedly performed in the shop I am responsible for is to cut small lengths, 1-2”, of right hand and left hand rolled thread rod into individual parts. Currently an operator does this on a horizontal band saw. He then will chamfer both ends of the rod and place them into containers based on their size.
·
I am envisioning a device which will eliminate most of his work and make the task more pleasant to do. Currently the task is so dreaded that no one ever wants to actually do it until absolutely necessary. If it could be made easier I think it would be more plausible to have more stocked inventory. ··
·
Theoretical device components:
·
· The device will contain the following KNOWN components. I say known because I’m still new to this and my programming experience with the BS2 is limited to a few hours.
·
Serial LCD w/ keypad interface
http://www.robot-electronics.co.uk/htm/Lcd02tech.htm
·
4x3 matrix keypad
Two 200step/rev resolution nema23 size stepper motors
1 small DC motor driving a cutting head – no speed control or feedback required
1 larger DC or AC motor to drive an abrasive chop saw
Several air cylinders to clamp and transport the raw rod stock
A few limit switches, and feedback switches
·
Theoretical device operation:
·
Upon start up the BS2 will retrieve the last used part length from the eeprom. It will also check the part count stored in the eeprom. After retrieving these two variables and storing them in ram it will begin a startup routine to turn the servo motors toward their limit switches.· The LCD will display the current stored part length and remaining part count if any. It will prompt the operator to press a key to change these settings or another key to continue operation. If the key relating to setup is pressed the value of “part length” may be adjusted.· Also quantity will be reset if desired. Once set the BS2 must check a micro switch in the part transfer area and determine if there is raw material in the machine. If it is, it will begin cutting rod. The machine will have a stationary clamp and a mobile clamp which ride on a linear guide, driven by a backlash compensated lead screw and stepper motor number 1. The rod will be fed in front of the stationary clamp just slightly. The stationary clamp will reclamp. The DC motor mounted on a second slide driven by a lead screw and stepper #2 will approach the rod. It will already be rotating and it will use rotating tools to chamfer the rod with two carbide cutting inserts. After this it will retract out of the way. The stationary clamp will release and the mobile clamp will drive inward to the part length. The stationary clamp will reclamp. An air solenoid will open on an air cylinder supporting the abrasive saw. Gravity and an orifice will bleed air from the cylinder supporting the saw allowing it to fall into the part and cut it off. The process will repeat until the switch in the loading area detects material is empty. It will then sound a buzzer to alert an operator to reload the machine. ·After this delay it will resume cutting until the value of parts to cut is reached. I have no desire for the machine to load its own material from racks or anything else. Hand loading is fine.
·
·
Thoughts:
· I understand the description is complicated especially for those who are not in the manufacturing mindset. I thought this project would be a great way for me to cut my teeth programming. I can justify the logic in my head and I like to think I am a fairly logical thinker. I believe if I can answer all conditions in my head the PLC can do this. ·I understand the BS2 has limitations. The LCD is serial with a remote pic controller. The keypad will be watched by that which frees up valuable cycles on the BS2.
·
My questions are as follows.
·
1)····· Do the experienced think I can write all the above into a program that will fit into the BS2.
2)····· What stepper drives should I look at? I considered two, “Little step-U” drivers that have limit inputs and absolute/incremental serial commands. Further reducing BS2 resources and personal programming skill.
3)····· Are there any devices that compare to the Little step-u? Perhaps something like the following with a serial interface? If so where can I find such an interface chip to purchase?
http://www.piclist.com/techref/io/stepper/linistep/index.htm#kits
·
Thank everyone for reading my document. I look forward to reading you thoughts.
·
Thanks in Advance,·
Philip MacDuffie
·
Post Edited (Phils88gt) : 11/1/2006 7:12:54 AM GMT
·· It’s a pleasure to finally have the time to post here, and perhaps retrieve a feasibility verdict based on the vast experience I assume lies in this forum. I obviously am seeking help, but I would like to at least offer the façade that I am not helpless. ·I’m a machinist, cnc programmer, and cad operator by day. I have some electronics background, and am definitely confident of my mechanical aptitude. I purchased a BS2 to learn how to program such a device for general application. My job does not require it, but I think I can apply a programmable PLC to my work.
·
·
Reason for constructing device:
·
··········· I wish to create a device which will remove a mundane task from the hands of a worker whom I deem his skills too great. A task repeatedly performed in the shop I am responsible for is to cut small lengths, 1-2”, of right hand and left hand rolled thread rod into individual parts. Currently an operator does this on a horizontal band saw. He then will chamfer both ends of the rod and place them into containers based on their size.
·
I am envisioning a device which will eliminate most of his work and make the task more pleasant to do. Currently the task is so dreaded that no one ever wants to actually do it until absolutely necessary. If it could be made easier I think it would be more plausible to have more stocked inventory. ··
·
Theoretical device components:
·
· The device will contain the following KNOWN components. I say known because I’m still new to this and my programming experience with the BS2 is limited to a few hours.
·
Serial LCD w/ keypad interface
http://www.robot-electronics.co.uk/htm/Lcd02tech.htm
·
4x3 matrix keypad
Two 200step/rev resolution nema23 size stepper motors
1 small DC motor driving a cutting head – no speed control or feedback required
1 larger DC or AC motor to drive an abrasive chop saw
Several air cylinders to clamp and transport the raw rod stock
A few limit switches, and feedback switches
·
Theoretical device operation:
·
Upon start up the BS2 will retrieve the last used part length from the eeprom. It will also check the part count stored in the eeprom. After retrieving these two variables and storing them in ram it will begin a startup routine to turn the servo motors toward their limit switches.· The LCD will display the current stored part length and remaining part count if any. It will prompt the operator to press a key to change these settings or another key to continue operation. If the key relating to setup is pressed the value of “part length” may be adjusted.· Also quantity will be reset if desired. Once set the BS2 must check a micro switch in the part transfer area and determine if there is raw material in the machine. If it is, it will begin cutting rod. The machine will have a stationary clamp and a mobile clamp which ride on a linear guide, driven by a backlash compensated lead screw and stepper motor number 1. The rod will be fed in front of the stationary clamp just slightly. The stationary clamp will reclamp. The DC motor mounted on a second slide driven by a lead screw and stepper #2 will approach the rod. It will already be rotating and it will use rotating tools to chamfer the rod with two carbide cutting inserts. After this it will retract out of the way. The stationary clamp will release and the mobile clamp will drive inward to the part length. The stationary clamp will reclamp. An air solenoid will open on an air cylinder supporting the abrasive saw. Gravity and an orifice will bleed air from the cylinder supporting the saw allowing it to fall into the part and cut it off. The process will repeat until the switch in the loading area detects material is empty. It will then sound a buzzer to alert an operator to reload the machine. ·After this delay it will resume cutting until the value of parts to cut is reached. I have no desire for the machine to load its own material from racks or anything else. Hand loading is fine.
·
·
Thoughts:
· I understand the description is complicated especially for those who are not in the manufacturing mindset. I thought this project would be a great way for me to cut my teeth programming. I can justify the logic in my head and I like to think I am a fairly logical thinker. I believe if I can answer all conditions in my head the PLC can do this. ·I understand the BS2 has limitations. The LCD is serial with a remote pic controller. The keypad will be watched by that which frees up valuable cycles on the BS2.
·
My questions are as follows.
·
1)····· Do the experienced think I can write all the above into a program that will fit into the BS2.
2)····· What stepper drives should I look at? I considered two, “Little step-U” drivers that have limit inputs and absolute/incremental serial commands. Further reducing BS2 resources and personal programming skill.
3)····· Are there any devices that compare to the Little step-u? Perhaps something like the following with a serial interface? If so where can I find such an interface chip to purchase?
http://www.piclist.com/techref/io/stepper/linistep/index.htm#kits
·
Thank everyone for reading my document. I look forward to reading you thoughts.
·
Thanks in Advance,·
Philip MacDuffie
·
Post Edited (Phils88gt) : 11/1/2006 7:12:54 AM GMT
Comments
This is a good application for a Stamp II.
I use them all the time in Plasma and Flame Cutting Machine Rebuilds.
The 2 big things to look out for is:
(1) The electrical noise from the motors/solenoids that are being controlled.
Optical isolation is a must.
(2) Emergency Stop Circuit. This must stop all motion under any conditions.
I do not let the Stamp/PLC control this function.
I use a seperate circuit that controls the power to each sub system.
A Emergency Stop Switch is used to control the power to the Circuit.
The NEC (National Electrical Code) requires this switch to be designed for E-Stop Functions.
This means it will break the circuit even if its contacts get welded shut. The switch has no spring activated contacts and will break the connection if you "Mash the button"
Automation Direct is a good source for Industrial rated Switches and Relays. They also have a nice stepper drive and motors. I have used them in the past.
The software is quite simple to write. The problem is that the Stamp has no interupt inoput.
You need to have the software constantly looking at everything, while doing everything.
If it is looking for a switch closure, you need to make sure you are still monitoring the motors and other operations as well.
I have a PC board I use that has 16· I/O positions for Solid State I/O Modules.
Input and Output modules can be used in any position, and the modules provide the isolation.
I have used them in my own projects for about 10 years.
I·could supply one, at my cost, if you are interested.
Thank You,
Alan Bradford
Plasma Technologies
www.plasmatechnologies.com
You would have to be classed as a "dream client".......one that actually knows what he wants and has thought the process through!
You would have no difficulty doing this project yourself. There is lots of help here for the asking plus you can have a look at the list of consultants elsewhere on the Parallax site, if you need to hire someone due to time constraints.
This project can be done either with a Stamp or a small PLC. At the end of the day, the hardware will be similar. At this level of complexity, the Stamp may be a bit more cost-effective if serial communication is required to LCD's or stepper controllers.
Cheers,
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Tom Sisk
http://www.siskconsult.com
·
RANT
· Funny you should mention CNC plasma systems. The shop I work for has a cnc plasma system. For the time I have spent fixing all the things it actually needs to work I could have built the entire thing myself! Their THC is my largest source of frustration. I just purchased an Ebay special THK linear guide to replace the utter garbage the thing came with. I would wager I get at LEAST 0.050” torch angular deflection because of the deplorable plastic slides they provide for the THC. My parts look like Smile and I am back reinventing the wheel. Which reminds me, what exactly am I paying them for? To place a signal generator, applied motion drives, and a relay into a new cardboard box. The end result: I am miserable and they profit. Sounds like the motto of American business to me.
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/RANT
·
··········· Now that I’m finished crying like a schoolgirl I wanted to mention I am aware NEC requires an E-stop on everything. In fact I had to add one to the CNC plasma since it also was lacking one. Here was my plan. I am not 100% on this, but I seem to recall the “Little step-u” having an emergency stop input. I could stop the steppers directly, and the E-stop could also break the power supply via a relay to the abrasive saw and the chamfer tool motor. Granted the BS2 would continue to spew signals out, and loose count of the parts made. This is not exactly elegant, but I think in an “Emergency” you can stand to restart the machine when it is safe. This also takes the programming load off me, removes the need for interrupt capability, and removes wasted processor time to poll the switch after every line of code. ·I considered mentioning that I had some plan for this, but I was not sure if my first post new on this forum was overwhelming or not. On that note I opted to leave it out.
·
Many thanks for the offer on the I/O board. At this point I will have to gracefully decline. As I mentioned I’m doing this for the experience of doing it. If I should fail or am unable to build whatever simple circuitry is needed to interface the stamp to my machine I would like to keep this option open.
·
Tom,
·· I’m not exactly sure what to say. I guess I must admit I’m a bit flattered. ·The forum I frequent is automotive related and rather technical. On that forum you had better have your material sorted and all bases covered before you distract the group with a question that could have been answered by a simple search. Usual recourse is a verbal lashing or dismissal from the forum on your first offence. It sounds a bit harsh, but it was necessary to keep the signal to noise ratio high. Members are encouraged to read the entire content of the site first which took me about 2 years. After following those simple instructions there is almost nothing to talk about, unless of course it is important. When I came here I tired to go back into the archives but most of the posts are very specific, “Help me with XXX”. Unfortunately I was not able to even come up with a search query that would answer the above. My only options were to sit on the outside and wonder or just go for it and hopefully I can provide the impression I’m not looking for a hand out. ·It appears as though I have succeeded. I’m not seeking a free lunch and I KNOW I have a copious amount of information to learn about the stamp and its limits. My problem is such. I purchased the stamp to learn some programming. Now I have it here and I followed the stamps in class tutorial book. I did not exactly have many of the things I needed to do these experiments, but I tried to understand what is actually happening. I then purchased the previously mentioned LCD02 device. I played with it and feel I have learned a great deal. Not so much that the LCD is a complicated device, but I was excited to play with it and had to just bang code in on the fly to do that. Previously I had a guide, but this time I just had to attempt what I thought I knew. I was successful and now I need a “project” to continue to hold my interest. This may just be that project.
·
All,
· This project is not being funded by my work it is all out of pocket. I’m sure if this thing works, my boss would refund me what it cost to construct. Do not think for a second I can recoup the cost of learning and thinking about it. My main goal is to learn, but making a useful device is just icing on the cake. I’m certain I have plenty of newbie questions to ask and mistakes to make. I’m glad it appears my project is feasible and I will begin collecting parts to build the mechanicals. (Which ironically for me is the easy part.)
·
Could someone please answer this?
· My question is answered. My idea is workable. My new focus is stepper drive. To discuss that do I continue on in this thread or is it protocol to let this thread die and start a new one?
·
· Thanks,
· Philip MacDuffie
·
·
·
I'd also recommend building a simple 'test-bed' set of hardware -- perhaps just a few switches and LED's to represent control inputs and system decision outputs -- that you could interface a BOE (Board Of Education) to, that you would use to debug your application. It's a lot easier to see that the 'activate trim saw' signal happened at the 'right time' on an LED, than it would be to put all this machinery together 'merely' for testing.
Plus, you'll want to do LOTS of 'test runs' to validate the system under both 'normal' and 'broken' conditions. This is much easier with a small test-bed than with the real thing.
Of course, your 'final' integration tests will have to be done with the 'real thing' -- but that will go much smoother and take much less time if 99% of your conceptual testing has been done on the test-bed.
I have built some XY tables using stepper motors and used MACH2 software (free versions available) using off the shelf stepper driver boards. Parallel port interface, just about any old computer will do. I use Windows2000 for the operating system. (XP has some issues with ports)
http://www.artofcnc.ca/DownLoads.htm
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Think outside the BOX!
Also, for any chip, the earthlcd touch screens would make a nice control panel.