[jayeff1]

We've asked Okuma for a solution to a problem with the rotate speed of the "Ready Station" swing arm for "heavy" tools. When a tool is identified as "heavy", the rotate speed of the swing arm from the spindle to the ready station is reduced from a normal tool - however the speed of the "Ready Station" swing arm as it rotates away from the ready station back to the matrix swing arm position remains at the same speed as a normal tool, resulting in the tool occasionally being ejected out of the "Ready Station " swing arm grippers. This makes a mess of the ejected tool and the control alarms out because the ejected tool is not deposited into matrix carrier.
We are looking for a way to slow down the speed of the "Ready Station" swing arm or a way to adjust the accel/decel curves for the motor speed. The same Okuma motor/drive combination is used for the "Ready Station" swing arm as is used on each of the other axis. Okuma has given us many things to try, nothing has worked. The last response from Japan was that it was not possible to modify the arm speed.
Has anyone else experienced this issue?

[deadlykitten]

hy, there had been recent threads about arm swing speed

http://www.cnczone.com/forums/okuma/...arm-speed.html
http://www.cnczone.com/forums/okuma/...ing-tools.html

maybe the guys that posted those have a solution ... maybe


my 1st thought when i read yours was to craft an arm than can deliver better grip; this is just an idea; actually i never had problems with my arm, so i don't know exactly it's dimensions and stuff, but there may be some pins that grip the toolholder ... maybe something may be increased

i have no clue about how to tune a motor; i think more mechanical

[jayeff1]

"maybe the guys that posted those have a solution ... maybe"

Thanks for the links - I missed them in my search for similar type problems


"my 1st thought when i read yours was to craft an arm than can deliver better grip; this is just an idea; actually i never had problems with my arm, so i don't know exactly it's dimensions and stuff, but there may be some pins that grip the toolholder ... maybe something may be increased"

We have looked at the tool retention mechanism - it is functioning properly, just not sure if the original design anticipated the heavy load at the normal rotate speed - might have have been an assumption that "heavy" speed would affect all three rotate motors.
The rotate motor is not direct coupled to the arm, it is driven through a timing belt, so we've kicked around changing the pulley ratios to reduce the rotate speed on the arm. Our concern is that we would exceed an event timer within the tool exchange routine.

[deadlykitten]

hy i took a closer look at my arm ( image 1 ) it swings in a horizontal plane

i guess your swings in a vertical plane

for mine, i can say that the grip mechanism works, but if it would work vertical, than it may lose some holders

this arms may be similar, even if on different machines

in image 2 bottom side, i draw a fast sketch of mine; the fixator does not allow the holder to rotate ( only to drop in your case ) ; there is some kind of block side mechanism, which i guess is always tensioned by a spring; i tried to push it by hand, and i did not succed, so there may be no spring; however, this may work even static, because on a horizontal swing plane forces are lower compared to a vertical swing plane

in image 2 upper side, i draw a better grip solution, which should work on a spring; idea is to increase the arch arround the toolholder the spring travel is depending on this arch, and i represent it in yellow color ... this will lead to increased torque on the arm each time it will come in contact with a toolholder, respectively each time it will release a toolholder in the spindle / pot

default arch is 180; i think you should consider at least 180 + 30 .. 35 ... 45 [ max ]
...... +45 works without a big spring force
...... +30 would require more tension from the spring

the arm should have a torque monitor; the arch on the arm should not require more than max_admisible_torque * 65%, so to say

if there will be problems with too much torque on the arm, than there may be another solution that does not require a spring, thus it does not increase the torque on the arm, but it will increase the traction ( axial forces ), and the arm will always be tensioned; thus, another variant

[deadlykitten]

We have looked at the tool retention mechanism - it is functioning properly, just not sure if the original design anticipated the heavy load at the normal rotate speed - might have have been an assumption that "heavy" speed would affect all three rotate motors.

that arm may be designed for more than 1 cnc, for bought vertical & horizontal swing plane

differences between them for same toolholder shank may be minimal; i don't know

The rotate motor is not direct coupled to the arm, it is driven through a timing belt, so we've kicked around changing the pulley ratios to reduce the rotate speed on the arm

if you can try, and put everithing back how it was, than why not

Our concern is that we would exceed an event timer within the tool exchange routine.

in the attached file are the steps for the swing procedure; maybe that includes your machine ... more than this i can not tell

however, maybe there are durations checks, as you said, or maybe there are mechanical confirmations, thus no tick-tock

some electronist should tune that motor ... kindly !