Rod
Member
Yeppers!
Make it happen!
Then, we'll play with a backgage
Rod (The CNC Dude)
Make it happen!
Then, we'll play with a backgage
Rod (The CNC Dude)
CYCLE HOLD - your thoughts and feedback
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- Start date
Terry Woods
Member
- Join Date
- Apr 2002
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- 3,170
Dan,
What do you mean by... "CYCLE HOLD is done"?
What do you mean by... "CYCLE HOLD is done"?
Rod
Well if I get near a shear I will see what I can do. In the class room I don't know if we have stuff on hand to simulate one. Liked the laser cutter though.
Terry
By CYCLE HOLD is done I meant it is commonly used feature of a program
Thanks for thoughts and questions - they make me think and learn.
Dan Bentler
Well if I get near a shear I will see what I can do. In the class room I don't know if we have stuff on hand to simulate one. Liked the laser cutter though.
Terry
By CYCLE HOLD is done I meant it is commonly used feature of a program
Thanks for thoughts and questions - they make me think and learn.
Dan Bentler
Terry Woods
Member
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- Apr 2002
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Dan,
Take a look at my last post in this thread...
http://www.plctalk.net/qanda/showthread.php?t=14021
Take a look at my last post in this thread...
http://www.plctalk.net/qanda/showthread.php?t=14021
Terry,
That clarifies what I have been thinking about - at least now I have a better idea of what the questions are.
One of my previous tasks (where I learned to use Sequencer) was a washer. It allowed to open the lid and restart where left off when reshut. Somewhat the same as CYCLE HOLD idea I have in mind the more I think about it the more I think they are identical.
I think I am going to give some thought on making the CYCLE HOLD a little more advanced than the washer lid ie about how to
1. Backtrack thru the program to where last left off (say on line 25)
2. Restart at line 20.
This may be a little advanced for me at this stage of education.
Let me talk to my instructor and see what he knows of it.
I also must stay with the goals of the project wich are to learn analog and stepper motor.
I am glad you linked this info - now I can go find it in the future.
Dan
Dan Bentler
That clarifies what I have been thinking about - at least now I have a better idea of what the questions are.
One of my previous tasks (where I learned to use Sequencer) was a washer. It allowed to open the lid and restart where left off when reshut. Somewhat the same as CYCLE HOLD idea I have in mind the more I think about it the more I think they are identical.
I think I am going to give some thought on making the CYCLE HOLD a little more advanced than the washer lid ie about how to
1. Backtrack thru the program to where last left off (say on line 25)
2. Restart at line 20.
This may be a little advanced for me at this stage of education.
Let me talk to my instructor and see what he knows of it.
I also must stay with the goals of the project wich are to learn analog and stepper motor.
I am glad you linked this info - now I can go find it in the future.
Dan
Dan Bentler
Terry,
I have read your post above and agree completely, but punching operations are pretty special, most of the high speed punching that I have worked on, the actual punching is almost completely mechanical and so the PLC won't know where the punch was in the punch cycle (it just knows "punch now", "punch finished")it will probably know the punch position but cannot restart from that point. What I do is, if a machine stop occurs during a punching cycle, eject the blank (or what's left of it as it probably compromised anyway) and reset the machine to its start postion using a known safe sequence. Other types of machine may be more tolerant of stops (e.g. a washing machine) or some machines may be ok to stop during some part of its cycle ( i.e. a compression moulding machine during its cure time)
The sort of punching machines I am talking about run at between 400 and 1200 strokes per minute. Here is a typical machine from Bruderer
Dan, what a PLC programmer has to do is look at the machine and its process and agree with the end user's manufacturing engineers etc. exactly what must happen in the event of a fault, then agree a SAFE way of applying that to the machine.
This site has some of the best Machinery safety information.
Or this site for the USA
I have read your post above and agree completely, but punching operations are pretty special, most of the high speed punching that I have worked on, the actual punching is almost completely mechanical and so the PLC won't know where the punch was in the punch cycle (it just knows "punch now", "punch finished")it will probably know the punch position but cannot restart from that point. What I do is, if a machine stop occurs during a punching cycle, eject the blank (or what's left of it as it probably compromised anyway) and reset the machine to its start postion using a known safe sequence. Other types of machine may be more tolerant of stops (e.g. a washing machine) or some machines may be ok to stop during some part of its cycle ( i.e. a compression moulding machine during its cure time)
The sort of punching machines I am talking about run at between 400 and 1200 strokes per minute. Here is a typical machine from Bruderer
Dan, what a PLC programmer has to do is look at the machine and its process and agree with the end user's manufacturing engineers etc. exactly what must happen in the event of a fault, then agree a SAFE way of applying that to the machine.
This site has some of the best Machinery safety information.
Or this site for the USA
Terry Woods
Member
- Join Date
- Apr 2002
- Posts
- 3,170
JohnW (1 of 2),
Dan is a student.
He is exploring the possibilities in programming. He is trying to explore those possibilities in terms of relatively real processes. In the past, he has indicated that he wants to follow normal practices including the exploration of the various programming methods as well as recognizing and handling safety issues. I applaud him for his drive and ambition. He appears to be doing well.
However, whenever any student poses a project, a bunch of Chicken Littles begin running around yelling "Safety First! Safety First! LOCK-OUT/TAG-OUT! Safety First!"
Safety certainly is very important.
However, is this the time? Is it practical to design a process (program) around a safety device?
In most cases, the Safety factors are designed outside of the program.
Now, as to how those devices are actually incorporated into the final design... there are several valid methods. The exact method employed depends on the nature of the particular process.
Method-1: The E-Stop (in whatever form) kills power to EVERYTHING! (Including the PLC.)
In this case, the program is not aware of any E-Stop condition. The E-Stop condition simply turns OFF everything. This is a HARD-WIRED method... it is NOT a programming issue at all!
Method-2: The E-Stop (in whatever form) kills power to all Outputs. (The PLC and Inputs remain energized.)
In this case, the program IS aware of the E-Stop condition. The E-Stop condition turns OFF power to ALL output devices AND, at the same time, provides a signal to a PLC Input that the condition exists. This too is a HARD-WIRE method... however, in this case, there are programming concerns.
As long as the PLC is powered, the program can "know" that an E-Stop condition exists. Under this method, the program should be written to recognize and handle the E-Stop condition. While in this condition, the various modules in the program calling for activity (based more on Internal Relays than current input conditions) should be driven to cancel any "calls" for particular output activities.
Now, even though the process is under an E-Stop condition, believe it, or not, in some applications, it is possible for certain conditions to change.
While the E-Stop condition exists, and as long as the PLC is energized, if changes in the process-status are acceptable, then the program can simply continue to monitor input devices and can continue to use Internal Relays to track changes in process-status. (Plan carefully!)
In this case, when the E-Stop condition is removed, the process "knows" the "situation". Using that information, the process can "resume" running according to some particular "recovery process". The "recovery process" has to be designed carefully so as to make the resumption occur without creating new problems.
Now, in some case, these changes in process-status conditions might not be acceptable. If the program "knows" that an E-Stop condition exists, then the program can "watch" to see that the required conditions are maintained.
For example...
... a hydraulic ram is used to control the elevation of a particular device. There is a Temposonic indicating the position of the device.
The E-Stop causes power to the direction valve and the fluid source (pump) to be de-energized. Under this condition, the valve and cylinder is supposed to hold the device in position... however, there is this teeny, tiny, little leak in the lines or valve. Since the program "knows" that an E-Stop condition exists, it also "knows" that the device is not allowed to move. Since the program is still running, it can track the position indicated by the Temposonic. If the position changes by some particular amount, or to some particular value, then... since the device is NOT allowed to move under this condition, it would be nice to know that the cylinder is failing to hold its position.
Since the program is still running, it can detect a change in position... the program can cause an alert to be displayed on the HMI. An operator can press a button to acknowledge the alert.
Being the Computer...
Hmmm... the alert is on, but there is no acknowledgement.
I wonder if anyone of those idiots is even looking at the HMI?
Damn! Unless I see an acknowledgement, I have no way of knowing... maybe yes... maybe no.
Gee, it sure would be nice to be able to force someone's attention and then aggrevate them into providing a response...
...but then... that would mean turning on an Output... wouldn't it?
Hmmm.... can't do that under Method-1 or Method-2... sounds like a case for a different Method.
Method-1 and Method-2 are fairly common. The choice is usually related to the complexity of the particular process. If Method-2 is not required, then use Method-1. A judgement has to be made. I have several processes that use Method-1 and several that use Method-2.
Method-3: The E-Stop (in whatever form) kills power to particular Outputs (or not)... depending on particular program/process conditions.
Method-3 is less common. It is far more complicated and has certain risks. However, sometimes, this is the best choice. Whether or not this particular method should be used depends on what would happen if either Method-1 or Method-2 is used. If using Method-1 or Method-2 would make a bad situation worse, then, maybe this is the best way is to develop a particular E-Stop handler (sequence). This would bring the process to a "SAFER" stop condition. This, of course, means that the PLC has to be energized, the Inputs energized, and certain Output power is controlled.
Method-3 should NOT be used unless Method-1 or Method-2 causes more problems than it prevents. Employing this choice must be considered very, very carefully!.
To those of you that say you can't see any possible reason for using Method-3, I can only say, you simply haven't been around the block very many times. Just because you haven't seen everything there is to see, that is no reason to place your limited views on those that have seen more. (BTW, I am NOT suggesting that I've seen everything there is to see... but I have seen situations, and currently have a situation, where Method-3 is the preferred method.)
Even rookie designers know that the safety concerns must be accounted for. However, they simply need to decide the particular method they plan to use. It is best to start assuming Method-1. Then, as the design process develops, they might find a need to use Method-2 instead. Method-3 comes in with only the more complex processes.
In terms of the "learning process", using nothing more than output lights or bench devices, it is entirely reasonable to assume that Method-1 will be employed.
JohnW (2 of 2),
Second... Regarding the "HOLD CYCLE" and "RESUME" discussion...
This is part of the discussion with Rod where he stipulated that he was trying to find a way to resume running WITHOUT blowing off an uncompleted blank. As Rod indicated...
"This also HELPS prevent scrapping a valuable blank part ( scrapped two 4' x 8' x 1" blanks AND an $800 tool two weeks ago!)"
Rod wants, very badly, not to have to "blow the blank!"
So, your...
"What I do is, if a machine stop occurs during a punching cycle, eject the blank (or what's left of it as it probably compromised anyway) and reset the machine to its start postion..."
...simply doesn't apply. It's nice for you that the requirements placed on your particular process are so simple that you (the end-user) can afford to "blow a blank".
At no point did I suggest that a punch cycle be restored to a position that places the punch in mid-stroke.
What I suggested was that a particular punch sequence might consist of one to several strikes before changing to the next tool or indexing the blank. I then indicated that a decision needed to be made as to which particular strike-cycle to return to.
Apparently, I didn't make it clear enough what I thought was the general form of any punch cycle...
"Load the Part"
- "Loading the Part"
- "Part has been Loaded"
"Punch Part"
--- "Punch with Tool-1"
----- "Punching the Part"
----- "Part has been Punched"
*
*
*
--- "Punch with Tool-X"
----- "Punching the Part"
----- "Part has been Punched"
"Unload Part"
- "Unloading the Part"
- "Part has been Unloaded"
With respect to "Punching the Part", the smallest, indivisible, basic action in an individual punch-operation is...
----- "Punching the Part"
This requires that the punch be in position to "BEGIN" a punch action.
If the particular punch-action involves several strikes then it is a matter of deciding which strike to start with. In any case, a strike begins with the punch at the home position.
Just because one can "afford" to "blow a blank", that doesn't mean that is the only way available to handle the situation. What if one can not "afford" to "blow a blank"?
If the cost of unnecessarily "blowing a blank" is too extreme, AND, if an appropriate programming method MIGHT can be applied to SAVE THE BLANK then, by all means possible, that method SHOULD be applied!
Depending on the particular product being processed, it might be extremely costly to simply "blow a blank". Think Globally (in terms of your Customers), act Locally (in terms of your efforts for that Customer)!
The abilities provided by the basic programming capabilities in all reasonable PLCs allows you to do what has to be done... it is only a matter of YOU choosing to do what has to be done...
The question is... ARE YOU UP TO THE TASK?
Dan is a student.
He is exploring the possibilities in programming. He is trying to explore those possibilities in terms of relatively real processes. In the past, he has indicated that he wants to follow normal practices including the exploration of the various programming methods as well as recognizing and handling safety issues. I applaud him for his drive and ambition. He appears to be doing well.
However, whenever any student poses a project, a bunch of Chicken Littles begin running around yelling "Safety First! Safety First! LOCK-OUT/TAG-OUT! Safety First!"
Safety certainly is very important.
However, is this the time? Is it practical to design a process (program) around a safety device?
In most cases, the Safety factors are designed outside of the program.
Now, as to how those devices are actually incorporated into the final design... there are several valid methods. The exact method employed depends on the nature of the particular process.
Method-1: The E-Stop (in whatever form) kills power to EVERYTHING! (Including the PLC.)
In this case, the program is not aware of any E-Stop condition. The E-Stop condition simply turns OFF everything. This is a HARD-WIRED method... it is NOT a programming issue at all!
Method-2: The E-Stop (in whatever form) kills power to all Outputs. (The PLC and Inputs remain energized.)
In this case, the program IS aware of the E-Stop condition. The E-Stop condition turns OFF power to ALL output devices AND, at the same time, provides a signal to a PLC Input that the condition exists. This too is a HARD-WIRE method... however, in this case, there are programming concerns.
As long as the PLC is powered, the program can "know" that an E-Stop condition exists. Under this method, the program should be written to recognize and handle the E-Stop condition. While in this condition, the various modules in the program calling for activity (based more on Internal Relays than current input conditions) should be driven to cancel any "calls" for particular output activities.
Now, even though the process is under an E-Stop condition, believe it, or not, in some applications, it is possible for certain conditions to change.
While the E-Stop condition exists, and as long as the PLC is energized, if changes in the process-status are acceptable, then the program can simply continue to monitor input devices and can continue to use Internal Relays to track changes in process-status. (Plan carefully!)
In this case, when the E-Stop condition is removed, the process "knows" the "situation". Using that information, the process can "resume" running according to some particular "recovery process". The "recovery process" has to be designed carefully so as to make the resumption occur without creating new problems.
Now, in some case, these changes in process-status conditions might not be acceptable. If the program "knows" that an E-Stop condition exists, then the program can "watch" to see that the required conditions are maintained.
For example...
... a hydraulic ram is used to control the elevation of a particular device. There is a Temposonic indicating the position of the device.
The E-Stop causes power to the direction valve and the fluid source (pump) to be de-energized. Under this condition, the valve and cylinder is supposed to hold the device in position... however, there is this teeny, tiny, little leak in the lines or valve. Since the program "knows" that an E-Stop condition exists, it also "knows" that the device is not allowed to move. Since the program is still running, it can track the position indicated by the Temposonic. If the position changes by some particular amount, or to some particular value, then... since the device is NOT allowed to move under this condition, it would be nice to know that the cylinder is failing to hold its position.
Since the program is still running, it can detect a change in position... the program can cause an alert to be displayed on the HMI. An operator can press a button to acknowledge the alert.
Being the Computer...
Hmmm... the alert is on, but there is no acknowledgement.
I wonder if anyone of those idiots is even looking at the HMI?
Damn! Unless I see an acknowledgement, I have no way of knowing... maybe yes... maybe no.
Gee, it sure would be nice to be able to force someone's attention and then aggrevate them into providing a response...
...but then... that would mean turning on an Output... wouldn't it?
Hmmm.... can't do that under Method-1 or Method-2... sounds like a case for a different Method.
Method-1 and Method-2 are fairly common. The choice is usually related to the complexity of the particular process. If Method-2 is not required, then use Method-1. A judgement has to be made. I have several processes that use Method-1 and several that use Method-2.
Method-3: The E-Stop (in whatever form) kills power to particular Outputs (or not)... depending on particular program/process conditions.
Method-3 is less common. It is far more complicated and has certain risks. However, sometimes, this is the best choice. Whether or not this particular method should be used depends on what would happen if either Method-1 or Method-2 is used. If using Method-1 or Method-2 would make a bad situation worse, then, maybe this is the best way is to develop a particular E-Stop handler (sequence). This would bring the process to a "SAFER" stop condition. This, of course, means that the PLC has to be energized, the Inputs energized, and certain Output power is controlled.
Method-3 should NOT be used unless Method-1 or Method-2 causes more problems than it prevents. Employing this choice must be considered very, very carefully!.
To those of you that say you can't see any possible reason for using Method-3, I can only say, you simply haven't been around the block very many times. Just because you haven't seen everything there is to see, that is no reason to place your limited views on those that have seen more. (BTW, I am NOT suggesting that I've seen everything there is to see... but I have seen situations, and currently have a situation, where Method-3 is the preferred method.)
Even rookie designers know that the safety concerns must be accounted for. However, they simply need to decide the particular method they plan to use. It is best to start assuming Method-1. Then, as the design process develops, they might find a need to use Method-2 instead. Method-3 comes in with only the more complex processes.
In terms of the "learning process", using nothing more than output lights or bench devices, it is entirely reasonable to assume that Method-1 will be employed.
JohnW (2 of 2),
Second... Regarding the "HOLD CYCLE" and "RESUME" discussion...
This is part of the discussion with Rod where he stipulated that he was trying to find a way to resume running WITHOUT blowing off an uncompleted blank. As Rod indicated...
"This also HELPS prevent scrapping a valuable blank part ( scrapped two 4' x 8' x 1" blanks AND an $800 tool two weeks ago!)"
Rod wants, very badly, not to have to "blow the blank!"
So, your...
"What I do is, if a machine stop occurs during a punching cycle, eject the blank (or what's left of it as it probably compromised anyway) and reset the machine to its start postion..."
...simply doesn't apply. It's nice for you that the requirements placed on your particular process are so simple that you (the end-user) can afford to "blow a blank".
At no point did I suggest that a punch cycle be restored to a position that places the punch in mid-stroke.
What I suggested was that a particular punch sequence might consist of one to several strikes before changing to the next tool or indexing the blank. I then indicated that a decision needed to be made as to which particular strike-cycle to return to.
Apparently, I didn't make it clear enough what I thought was the general form of any punch cycle...
"Load the Part"
- "Loading the Part"
- "Part has been Loaded"
"Punch Part"
--- "Punch with Tool-1"
----- "Punching the Part"
----- "Part has been Punched"
*
*
*
--- "Punch with Tool-X"
----- "Punching the Part"
----- "Part has been Punched"
"Unload Part"
- "Unloading the Part"
- "Part has been Unloaded"
With respect to "Punching the Part", the smallest, indivisible, basic action in an individual punch-operation is...
----- "Punching the Part"
This requires that the punch be in position to "BEGIN" a punch action.
If the particular punch-action involves several strikes then it is a matter of deciding which strike to start with. In any case, a strike begins with the punch at the home position.
Just because one can "afford" to "blow a blank", that doesn't mean that is the only way available to handle the situation. What if one can not "afford" to "blow a blank"?
If the cost of unnecessarily "blowing a blank" is too extreme, AND, if an appropriate programming method MIGHT can be applied to SAVE THE BLANK then, by all means possible, that method SHOULD be applied!
Depending on the particular product being processed, it might be extremely costly to simply "blow a blank". Think Globally (in terms of your Customers), act Locally (in terms of your efforts for that Customer)!
The abilities provided by the basic programming capabilities in all reasonable PLCs allows you to do what has to be done... it is only a matter of YOU choosing to do what has to be done...
The question is... ARE YOU UP TO THE TASK?
Rod
Member
Weeozerzs!
Relaxe!!!!
Terry - as usual - has been able to define and display his knowledge MORE than adequately!!
A FAIRLY recent demo of the turret punch software is available here.
http://pccontrols.net/download.html (go to the turret demo download)
If you so choose to play with it it does support a multi-station turret punch press with a few 'test' programs to futz with. You may not save your new part, nor may you copy X/Y positions. Else the program is 'FULL BLOWN' - meaning that our customers BLOW IT UP QUITE REGULARLY!!!
When in either the Run Mode or Dry Run Mode you may hit STOP and either (using the Forward/Back buttons) do a step back through the program to the blown tool, replace same, jog the turret or table around, ETC; then hit Resume/Cycle Start and off you go.
As Terry stated the turret will rotate to the desired tool station first, the X/Y axes will resume position and punching will resume.
I only brought this to the table as an example of 'REAL WORLD' software, I never meant for it to be a discertation!
We have retrofits in the lower 48 states, Canada, Mexico and the Virgin Isles(I didn't get to do the installs in the Virgins)
Terry! You are too goood! Do you teach, or do you DO!!?? Or, better yet, both?
I did get some digital shots of a manual - only describes MACHINE LOCK - not what I wanted.
Pester ya later,
Rod (The CNC Dude)
Relaxe!!!!
Terry - as usual - has been able to define and display his knowledge MORE than adequately!!
A FAIRLY recent demo of the turret punch software is available here.
http://pccontrols.net/download.html (go to the turret demo download)
If you so choose to play with it it does support a multi-station turret punch press with a few 'test' programs to futz with. You may not save your new part, nor may you copy X/Y positions. Else the program is 'FULL BLOWN' - meaning that our customers BLOW IT UP QUITE REGULARLY!!!
When in either the Run Mode or Dry Run Mode you may hit STOP and either (using the Forward/Back buttons) do a step back through the program to the blown tool, replace same, jog the turret or table around, ETC; then hit Resume/Cycle Start and off you go.
As Terry stated the turret will rotate to the desired tool station first, the X/Y axes will resume position and punching will resume.
I only brought this to the table as an example of 'REAL WORLD' software, I never meant for it to be a discertation!
We have retrofits in the lower 48 states, Canada, Mexico and the Virgin Isles(I didn't get to do the installs in the Virgins)
Terry! You are too goood! Do you teach, or do you DO!!?? Or, better yet, both?
I did get some digital shots of a manual - only describes MACHINE LOCK - not what I wanted.
Pester ya later,
Rod (The CNC Dude)
rsdoran
Lifetime Supporting Member
This is where it got convoluted.
Quote leitmotif:
Where does he say anything about a punch press? That was my point early on, a drill press is completely different than a punch press, especially on the issue of safety.
As for the process he never fully stated how much of it was automatic...ie does it just drill/tap in auto and blank has to be positioned? OR is the blank on an automated table (like a mill) that can position the blank for multiple drilling or tapping?
The thread took a tangent away from a student trying to learn the basics of learning to program with steppers and analog involved. This person is a student but is also an experience maintenance/safety person so I am sure he can recognize any issues that may arise.
After Rods last post I am confused...is this a punch or a drill machine?
Terry Woods
Member
- Join Date
- Apr 2002
- Posts
- 3,170
Ron,
The post that JohnW was referring too, in this thread, was on a different thread (Initiated by Rod).
Both threads have a certain degree of commonality... That is why, at an earlier point, on this thread, I referred Dan to read my post to Rod on the other thread.
Ron, you have to be able to "Multi-task" to follow this whole thing.
Rod asked...
"Terry! You are too goood! Do you teach, or do you DO!!?? Or, better yet, both?"
I do both.
The post that JohnW was referring too, in this thread, was on a different thread (Initiated by Rod).
Both threads have a certain degree of commonality... That is why, at an earlier point, on this thread, I referred Dan to read my post to Rod on the other thread.
Ron, you have to be able to "Multi-task" to follow this whole thing.
Rod asked...
"Terry! You are too goood! Do you teach, or do you DO!!?? Or, better yet, both?"
I do both.
Rube
Member
Terry Woods said:
I just so happen to be using this method in the program I'm writing now.
I too would like to compliment Terry's as usual ability to enlighten.
Terry Woods
Member
- Join Date
- Apr 2002
- Posts
- 3,170
Thanks, Rube.
rsdoran
Lifetime Supporting Member
I have followed the whole thread. Originally Dan asked about safety and immediately the advice predominantly pertained to punch press type machinery. Original questions:
Post 2: http://www.plctalk.net/qanda/showpost.php?p=92986&postcount=2
A mild tangent insued then Rod discussed standard working sequences and you talked about the cycle hold aspect...
THEN we got the Europe standards are better Post 36:
http://www.plctalk.net/qanda/showpost.php?p=93362&postcount=36
Then we got back to the cycle hold part and you posted a link to the Karnaugh map thread.
Then it went back to talking about punch press
http://www.plctalk.net/qanda/showpost.php?p=94144&postcount=51
In your next post you also used punch press as an example.
Question #1: I dont think anyone addressed this.
Question #2: Many jumped on the safety part but how can you state what the safety issues may be if you dont know what the machine does? It was stated to be a drill press with multiple steps...ok what steps and where do they go?
Question #3: I dont have a clue...what does the machine do?
I will admit that your (Terrys') posts have been very informative on "how to" as they usually are.
I can see now I should have included the process -- so here it is
To keep things simple I chose to simulate a drill press used to drill multi (6) holes in a pipe flange.
Hydraulic pump is 3 phase motor driven.
VFD controls speed of motor.
The hydraulic motor driving the drill has a tach gen so
I can feed that volt signal to the PLC
and have the PLC use that to send another volt signal to the VFD
to speed or slow the hydraulic pump to speed or slow the drill motor.
Kinda convoluted I know and violates KISS but when you are working out of an existing inventory of left over parts etc what are you to do.
Here is sequence
1. Load part
2. Start hydraulic pump (it drives the drill bit motor and is used to set the clamps and indexer
3 Clamp part (probably will simulate with a manual switch)
4. PCL sends signal to servo valve to start drill motor (hydrualic)
5. Hole is drilled THRU the flange.
5a. I may have a piston to simulate a quill shaft up / down driver
- have not quite decided yet.
6. Drill retracts
7. Stepper motor rotates table 60 degrees
8. Index pin inserts into just drilled hole to finalize location of part -- probably will simulate with a manual switch.
Steps 4 thru 8 are repeated untill all holes are drilled.
I have noted that a lot of other posts do not describe the operation well then I DO IT TOO another live n learn.
Yeah there were a couple tangents and yet they were not tangents LOTO and the punch press discussions. EVEN IF they were tangential I found at the minimum reminders of things I should remember things to think about and new concepts.
THANKS for the help
Dan Bentler
To keep things simple I chose to simulate a drill press used to drill multi (6) holes in a pipe flange.
Hydraulic pump is 3 phase motor driven.
VFD controls speed of motor.
The hydraulic motor driving the drill has a tach gen so
I can feed that volt signal to the PLC
and have the PLC use that to send another volt signal to the VFD
to speed or slow the hydraulic pump to speed or slow the drill motor.
Kinda convoluted I know and violates KISS but when you are working out of an existing inventory of left over parts etc what are you to do.
Here is sequence
1. Load part
2. Start hydraulic pump (it drives the drill bit motor and is used to set the clamps and indexer
3 Clamp part (probably will simulate with a manual switch)
4. PCL sends signal to servo valve to start drill motor (hydrualic)
5. Hole is drilled THRU the flange.
5a. I may have a piston to simulate a quill shaft up / down driver
- have not quite decided yet.
6. Drill retracts
7. Stepper motor rotates table 60 degrees
8. Index pin inserts into just drilled hole to finalize location of part -- probably will simulate with a manual switch.
Steps 4 thru 8 are repeated untill all holes are drilled.
I have noted that a lot of other posts do not describe the operation well then I DO IT TOO another live n learn.
Yeah there were a couple tangents and yet they were not tangents LOTO and the punch press discussions. EVEN IF they were tangential I found at the minimum reminders of things I should remember things to think about and new concepts.
THANKS for the help
Dan Bentler
Rod
Member
Guilty as charged
I was using punch presses as a means to help demonstrate the Cycle Hold and 'step forward/back' on or more blocks in process.
It's the only example I have to offer that I know works.
Sorry for any confusion.
Rod (The CNC dude)
I was using punch presses as a means to help demonstrate the Cycle Hold and 'step forward/back' on or more blocks in process.
It's the only example I have to offer that I know works.
Sorry for any confusion.
Rod (The CNC dude)
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