These issues apply to the TT1800SY and Puma series subspindle machines.
We run turning machines 24 hours a day, for years, so this post is not about a problem that happens every day- it's more like a quarterly incident promoter. We have one of these issues about every 1800 run hours, but on specific types of parts they are over-represented, and probably occur every 200 hours.
The Ejector ends on these machines do not spin. We have to use ejector ends, because different parts have different diameters and geometries to eject to keep the processes running. The subspindle housing doesn't tolerate being full of chips. Chips can stop the ejector and leave the part in spindle to stovepipe and damage the ejector, they can also wear out seals in the subspindle and damage the subspindle, so these ends have to block chips period. There is no workaround for every part and often the work arounds eat time, and customers shouldn't perpetually lose time to a flawed ejection system even if every problem could be solved by strange methods of recalling tools and keeping holes just barely blind as long as possible.[/B]It's not terrifically uncommon to turn a part that, on the subspindle side, ends up with some chips passing through a bore. The non spinning ejectors get worn by chips during production runs, and that changes the geometry of the ejector ends.
Sometimes the chips rip the end off the ejector, attempting to spin the pneumatic actuator, bending the forks on the mount, or ruining the actuator.
Sometimes the deformed ejector ends (Deformed in process from wear from rotating chips on the non-rotating ends), become a different shape and stick the part on ejection, drawing it back inside. Then the machine moves to grab a new part and stuffs the non-ejected part into the penumatic actuator. That can damage the ejector or the hydraulic chuck closer the actuator is attached to.
Sometimes a turning tool turns the spindle in the right way for the ejector end to be grabbed by chips and jack screw against the part after thousands of parts are made (indicating this was process stable until it wasn't), and that created tremendous pressure on the actuator mounted pneumatic ejection system and can ruin a hydraulic actuator, blowing the seals, causing all the hydraulic fluid to evacuate in the chip pan.
The ejector end needs to be free spinning, capable of rotating with the part. This solves all of these issues!! Doosan has a team of engineers that apparently don't spend any time on this major issue. I've lost one pneumatic ejector system (the whole thing ruined), straightened forks at least 4 times, spun ends off maybe a dozen times. We've had one machine lose 3-4 hydraulic actuators, all over this issue.
I've got 8 of the subspindle turning machines, one more on the way, and we've reported this issue many times. This issue has never been solved by Doosan engineers.
Our Yama machines weren't great, but they had a simple, vastly superior ejector end that "floated" on the end of the pneumatic rod, and spun with the part- it was like washers and a tube on the end of the ejector rod, spring loaded forward and moving with the pneumatic rod. The shop made ejector ends were screwed into the rotating spring loaded tube rather than the pneumatic ejector end. I didn't take pictures of it and dimension it when I had a Yama because I didn't think the Doosan would have a flawed ejection system. The ejection system on the Yama had never been an issue (it was one of the best systems on the machine) so I had no reason to think these issues even existed.
If I had pictures of the Yama ejector, I would have made my own system by now. This is stupid. Doosan is supposed to care about machines working right. That's my impression of what the brand is supposed to be about.
Maybe Doosan engineers can call Yama Seiki and pay them as consultants to fix their problems. The customers will pay for a solution, but it's not traditionally our job to design it, and it should become std equipment on new machines.