Hardinge CHNC turret woes

[Karl_T]

I'm trying to get the turret working on a hardinge CHNC with a new Camsoft control. Its drove me to drink, I just said F%^& it and grabbed a cold one.

I can't get the turret to land on the locating lock pins reliably. It wants
to go just a bit to far in rotation.

The turret on this machine has two air devices. The turret index lifts the
turret and an air motor rotates it. There is also a turret stop solenoid
that engages a rod against a ratchet stop.

There are turret down (magnetic prox switch) and an eight position absolute
encoder for sensors.

First and foremost I'd like to know how the stop indexing logic is supposed
to work on the original machine. I'm finding that the turret stop solenoid
won't engage with the turret running, is this normal?
I have to stop the turret indexing(short of the locating lock pins), engage
the stop solenoid, and then try to bump the turret index up against the
ratchet stop. This goes past the locating stop pins when driven against it
hard(lot of force here). Once, I jammed the turret stop solenoid and had to
take the whole thing apart to free it up.

I'm guessing at this point. I'm thinking of trying a new (longer) ratchet
stop rod, the whole cross slide has to be dissembled to get at this. Then
I'll find out this ain't it.

If anybody know a pro hardinge repairman I can call, I'll gladly pay for
good advice.

Karl

[Al_The_Man]

I am not familiar with that particular set up and have no idea how it functioned originally, but to have an encoder or eight position sensor and use an air motor, sounds like a basic design flaw, all the one's I have been involved with have either had hydraulic with hydraulic slow down before position, hydraulic servo, or at least air-over-oil.
To get an air operated device to stop on a dime is asking a lot IMO.
Al.

[Karl_T]

The hydraulic powered turrets on my mazak M4 lathe had slow down and were a piece of cake to get running.

There are thousand and thousand of these CHNC lathes that have run production for years 24 X 7. I know they are reliable machines. But, I bet there are some tricks to this air turret.

Karl

[Metalmog]

I have a Feeler FNCH equivalent, and would be very interested if you solved your problem. I most likely will need to go through the same issues.

Mine has an air motor with solenoid and an air operated ratchet solenoid (both 6V DC) There is also a proximity switch and the 8 position absolute encoder. The encoder actually is 8 magnetic proximity switches, one for each position. The dog that triggers each switch is adjustable and will remain triggered for quite a bit of table movement (10 to 20 degrees). I should imagine that you can adjust this dog to trigger slighly early and thus have the table coast into position under it's own momentum until the proximity switch indicates the lock position. One should be able to release the ratchet after the trailing edge of the encoder pulse, which is way before the lock position is achieved. Finally I would put a timer on the trailing edge of the the position switch to turn on the motor briefly if the lock has not been reached, till it is achieved.

Short version explanation - adjust the tool position timing.

One more item. The ratchet arm appears to have an air damper on the other end. If the seals are worn, then the damper does not fully push the table back to the final lock position and makes it difficult to achieve lock.

[Metalmog]

I have a Feeler FNCH equivalent, and would be very interested if you solved your problem. I most likely will need to go through the same issues.

Mine has an air motor with solenoid and an air operated ratchet solenoid (both 6V DC) There is also a proximity switch and the 8 position absolute encoder. The encoder actually is 8 magnetic proximity switches, one for each position. The dog that triggers each switch is adjustable and will remain triggered for quite a bit of table movement (10 to 20 degrees). I should imagine that you can adjust this dog to trigger slighly early and thus have the table coast into position under it's own momentum until the proximity switch indicates the lock position. One should be able to release the ratchet after the trailing edge of the encoder pulse, which is way before the lock position is achieved. Finally I would put a timer on the trailing edge of the the position switch to turn on the motor briefly if the lock has not been reached, till it is achieved.

Short version explanation - adjust the tool position timing.

One more item. The ratchet arm appears to have an air damper on the other end. If the seals are worn, then the damper does not fully push the table back to the final lock position and makes it difficult to achieve lock.

[Metalmog]

I have a Feeler FNCH equivalent, and would be very interested if you solved your problem. I most likely will need to go through the same issues.

Mine has an air motor with solenoid and an air operated ratchet solenoid (both 6V DC) There is also a proximity switch and the 8 position absolute encoder. The encoder actually is 8 magnetic proximity switches, one for each position. The dog that triggers each switch is adjustable and will remain triggered for quite a bit of table movement (10 to 20 degrees). I should imagine that you can adjust this dog to trigger slighly early and thus have the table coast into position under it's own momentum until the proximity switch indicates the lock position. One should be able to release the ratchet after the trailing edge of the encoder pulse, which is way before the lock position is achieved. Finally I would put a timer on the trailing edge of the the position switch to turn on the motor briefly if the lock has not been reached, till it is achieved.

Short version explanation - adjust the tool position timing.

One more item. The ratchet arm appears to have an air damper on the other end. If the seals are worn, then the damper does not fully push the table back to the final lock position and makes it difficult to achieve lock.

[Karl_T]

After three complete code rewrites and the addition of another air solenoid, yes, the tool changer purrs like a kitten.

Turned into a HUGE JOB. My big issue was with the exhaust air flow setting (restrictor needle valve) If I set it slow, barely open, the turret would quit indexing after a few days. If I opened it up, then the turret would take off like a bat out of hell after a few days and miss the landing spot.

I added a "fast" exhaust air solenoid to start the turret up and around. When one encoder position away, close this. Now the turret will always pop up and start turning. The restrictor needle valve is set to barely let air out so it slows the turret right down when this "fast" exhaust solenoid closes.

Your turret sounds similar but slightly different. My macro wouldn't work for you.

BTW, new CHNCs have changed to a servo motor for turret index. If I were to do it over, I'd just buy the servo motor and add an axis to the Galil board for this.

Karl

[Metalmog]

I was considering changing to servo, but for different reason. Much as air driven is simple and forgiving I prefer not to have a big compressor banging away all the time. Problems with neighbours if this becomes a 24/7 thing.

It will have to wait till next year. Just thinking ... A simple DC motor and appropriate drive amp should work. This would be an ideal application for a simple stepper motor & drive.