Im totally new! Please help! Tool changer PLC

[mike^3]

I APPRECIATE ALL HELP!

I am trying to set up a tool changer on a lathe.

Disclaimer :

I have never used a PLC or the software to program a PLC.
I am very good with electronics and wiring diagrams.


Here are my questions...

1. Which PLC would be best for my application?
2. Which software do I need?
3. How would I program it?

My lathe has 8 positions, the PLC will receive a series of 4 signals for each tool changer position from the controller, then receive similar 4 signals from the toolchanger position encoder.

Here is the table from the controller to the PLC, if the controller requests a tool: (1) is (HI) 5v, and (0) is Low 0v, I can use 12v or 24v but would prefer to use the controller 5v logic, as I would need to add more relays in for higher voltages.


(these are inputs on the PLC from the cnc controller)
Tool# Pin 1 Pin 2 Pin 3 Pin 4
1 1 0 0 0
2 0 1 0 0
3 1 1 0 0
4 0 0 1 0
5 1 0 1 0
6 0 1 1 0
7 1 1 1 0
8 0 0 0 1

So lets say for example I wanted to get tool 3, from the table above, I would need the turret to spin until the PLC senses pin 1 and pin 2 to be HI.

This is the sequence for the turret.

If PLC senses Pin 1 and Pin 2 to be (1) HI 5v***from the controller, basically telling the PLC go get tool 3****
Then activate tool change script/macro/ladder

Activate output 5 (whichever output pin you want to set on the PLC)
Activate output 6

Then wait for Pins on the input from the tool changer SEE BELOW *****now these are going to be the same table as above but pins 5, 6, 7, and 8****

When the PLC senses that inputs 5 and 6 are HI (5v or 12v) then it knows its at tool 3 (from the turret encoder) and then

Deactivates output 5
Wait 1 second
Deactivates output 6

Then output a (HI) signal from the plc on any output you chose, ***this output pin will goto the controller and say, "hey, we are done, and you now have tool 3!"


********this is the inputs to the PLC from the tool changer, it is the same logic from the controller, just different pins**********
Tool# Pin 5 Pin 6 Pin 7 Pin 8 (these are inputs on the PLC)
1 1 0 0 0
2 0 1 0 0
3 1 1 0 0
4 0 0 1 0
5 1 0 1 0
6 0 1 1 0
7 1 1 1 0
8 0 0 0 1

I would need the ladder logic for all 8 tool change positions!

I appreciate any help! I know its not easy being new, and I will support this forum as I am new, and would like to help out others once I become Learned HAHA THANK YOU!

Mike!

 

[Steve Bailey]

What are you using to spin the tool turret?
What are "output5" and "output6" connected to?

 

[mike^3]

Hi! Thank you for the quick reply. Output v and output 6 are connected to a relay that close as a contact for an air motor and a stop pin that stops the turret. That's why we need to activate and deactivate output 5 and 6 to make the turret work properly. In sequence, 5 then 6.

Output 5 releases the stop pin and output 6 activates and deactivates air motor which spins the turret at a fairly constant rpm.


Thank u so much for your help
Does this clarify it a bit more ?

 

[Steve Bailey]

It sounds to me like a Click PLC from Automation Direct would handle this. It can handle 5 VDC inputs and the software for it is free.

You may need a few more signals than you've defined. There is probably something in the CNC that clamps the tool and a confirming signal that the tool is clamped. You probably need something similar on the changer side. You will need to define the sequence of events to transfer the tool between the turret and the lathe.

You're going to need to be able to rotate the turret to the empty position and transfer the current tool from the lathe to the changer before finding the desired tool and transferring it from the turret to the lathe.

 

[mike^3]

Hi,

I should explain the turret in brief detail. The lathe has the turret, which holds the tools, so the tools don't actually leave the turret.

Yes I will need to have a input for the tool seated input once the the tool change is completed. The cnc lathe is a chnc 2, you can see a video of how it works on line.

Which click plc model do I need? And any ideas for programming?

 

[Steve Bailey]

Which click plc model do I need?

I'm pretty sure all of the Click base units with DC inputs are 24 VDC, so you'll need to add the 5 VDC expansion module C0-08NDC-1. For 5 VDC outputs to the CNC controller you can use a base unit with relay outputs.

As to programming, if you wire the CNC outputs to the PLC inputs in the proper sequence, the Click will be able to convert the pattern of inputs into a number. It also has comparison instructions so you will be able to detect when the tool at the turret matches the requested tool.

 

[Ron Beaufort]

I don't want to needlessly complicate this project - but before you go too much further, double-check the machine's documentation and make sure that the term TTL doesn't appear in the input/output specifications ...

TTL stands for Transistor/Transistor Logic - and although 5 volts is being switched, SOMETIMES a simple relay closure won't do what you need ...

SOMETIMES a pull-up or a pull-down resistor is also needed ...

some PLC manufacturers make input/output modules specifically for this type of TTL operation ... there's a reason for that - SOMETIMES a simple relay contact closure won't work reliably ... robots and milling machines are common examples of this type of signal interfacing ...

good luck with your project ...

 

[Steve Bailey]

Good point Ron. Thanks for raising it.

 

[mike^3]

Hello! Thank you for your input!

I will buy a click PLC, the outputs from the turret encoder are either ON (12v) or off 0v, its is not like an encoder ttl. It is basically 8 transistors, that when a magnet goes by them, they become sinked, or sourced to 12v.

Then the 8 inputs goto a small chip that then turns it into 4 bit code, as seen above.

Im looking at CLICK PLC's, there are so many of them, which should I choose? I only need 8 inputs, and probably 8 outputs, preferably 8 relay outputs...that will close a contact with me supplying either ground or voltage to the relay terminals...

Thank you!!!

 

[mike^3]

I could use the Relay output of the PLC to trigger the output5 and 6, if it will happen quickly and reliably as you mentioned.

 

[jrwb4gbm]

Hi,

I should explain the turret in brief detail. The lathe has the turret, which holds the tools, so the tools don't actually leave the turret.

Yes I will need to have a input for the tool seated input once the the tool change is completed. The cnc lathe is a chnc 2, you can see a video of how it works on line.

Which click plc model do I need? And any ideas for programming?

The most valuable thing you need to know about programming any PLC is to clearly define each simple step in intricate detail on paper before ever attempting to write the ladder logic for it.
Others will program different from me but the next step for developing the ladder logic is make individual rungs with nothing on each rung but one hard output on each rung.Then develop each step on individual intermediate rungs to a soft output. Next after that you would combine all the soft outputs to drive whatever hard output that is needed. Be sure to label all inputs and outputs with something meaningful,. Be sure to comment each rung with a general definition as to what it is supposed to do. Always use and refer to any electrical diagrams that you have to coordinate the machine with the plc. There is more but maybe this will help you get started.

 

[Steve Bailey]

OK, I found some videos of Hardinge CHNC II lathes. Are you trying to replace a tool changer that no longer works or to retrofit a tool changer onto a lathe that doesn't have one?

The Click base units with DC inputs are all nominal 24 VDC. You may have to use two different expansion modules, one for the 5 VDC signals from the CNC to the Click, another for the 12 VDC signals from the turret encoder to the Click. Given that, it might be easier to use interposing signal conditioners and a Click base unit with 24 VDC inputs. You can easily get 5 VDC to 24 VDC and 12 VDC to 24 VDC conditioners.

 

[mike^3]

The chnc I retrofitted with a new control, I am keeping the same turret, the control cant handle the tool changer, that's why I need a plc to perform it, then tell the control im done..

 

[Steve Bailey]

Since the CNC controller you're using can't handle the tool changer, are you sure it will turn on and off the signals for the tool request?

 

[mike^3]

I can get away with not having 5vdc input on the click, what I will do is have the control output 4 signals to relays, and then the relays will give 24vdc to specific inputs on the click. same thing for the tool changer, the tool changer will apply 12vdc to a series of 4 inputs on 4 relays, turning them on and off, it will just trigger the 24vdc powersupply to the input of the PLC:

So, here could be the break down.

Motion controller puts out 5vdc to a specific tool request (see above table)
Then
5vdc (depending on if its one, or 2 or 3 relays) will trigger a 24vdc relay
Then
24vdc (triggered from 5vdc relay) will provide a HI/ON state to one of four inputs
Then
Control will have ladder logic saying that, depending on the logic table above, it will activate tool get sequence.

I.E. 24vdc is received on pin 2 of the PLC. (when pin 2 is HI activate tool sequence get tool 2)
The PLC will need to then activate output 1(can be any output you set, im just using one for simplicity) ***(this is to release the stop dog so the turret can spin)
Then
PLC needs to activate output 2 (turns on air motor which lifts turret and spins it)
Then
PLC needs to wait until pin 6 is active (24vdc) (triggered through another 5vdc relay to supply 24vdc to pin 6 of the PLC) ****this is the logic above which states that when looking for tool 2, pin 6 is HI and pin 5,7,and 8 are low.
Then
PLC sensed that input 6 is HI and 5,7, and 8 are low, deactivate output 1(engaged lock to stop turret)
Then
Wait 1 second
Then
Deactivate output 2 (stops the motor from spinning the turret (this is an air motor so it will be fine if we force it stop, its how it was originally designed.
Then
Activate output 4 (this will supply 24vdc to the motion controller say that it is at the right position and continue)

This process will repeat for every tool change, yet the inputs sensed will be different, the output will be the same.

Does this identify the ladder well?

Also, is there any plc that will take in 5vdc-12vdc? and output 5vdc? This would be awesome and would eliminate a lot of extra parts lol!

Thank you!

Mike