Okuma-howa act4 weird startup ritual

[sander96]

Hi, I have this weird startup ritual with my 92 okuma howa act4 lathe fanuc 15tf. When i first start up the machine in the morning and press machine ready, all the auxilaries suddenly switch on. Turret starts to turn endlessly, spindle changes gear, tailstock moves, work ready flashes, chuck open-close, tailstock sleeve goes forward. Seems like every possible output becomes active. First time it was very scary and almost crashed the machine. It takes a few minutes and machine goes back to normal and functions good for rest of day. If I let it wait 15 minutes before pressing machine ready, it doesnt go crazy. Has anybody experiencid this and should i be worried?

 

[angelw]

Hi, I have this weird startup ritual with my 92 okuma howa act4 lathe fanuc 15tf. When i first start up the machine in the morning and press machine ready, all the auxilaries suddenly switch on. Turret starts to turn endlessly, spindle changes gear, tailstock moves, work ready flashes, chuck open-close, tailstock sleeve goes forward. Seems like every possible output becomes active. First time it was very scary and almost crashed the machine. It takes a few minutes and machine goes back to normal and functions good for rest of day. If I let it wait 15 minutes before pressing machine ready, it doesnt go crazy. Has anybody experiencid this and should i be worried?

Haven't you answered your own question, with the "almost crashed the machine" comment?

What you've described is not normal; I have client's with Okuma Howa lathes and similar to all lathes I've ever worked with, don't have component assembles that run away as you describe. In the contrary, its typical for many features of a machine NOT to work (particularly in Auto Mode) until an initialization procedure has been carried out. For example, the turret index of some lathes won't work until an Index Initialization has been completed. I would be investigating and rectifying the condition you describe with your machine.

Regards,

Bill

 

[sander96]

Yes, its definitely not normal behaviour. I just thought maybe someone has some experience with a similar problem or has some idea what to look for.

 

[Garwood]

Yes, its definitely not normal behaviour. I just thought maybe someone has some experience with a similar problem or has some idea what to look for.

scope your DC power supplies. If it doesn't do it when you let it sit with the breaker on for awhile before you turn on the power it has something to do with electrolytic capacitors. You are reforming the capacitors by letting it sit with power on. Then it works fine.

 

[sander96]

scope your DC power supplies. If it doesn't do it when you let it sit with the breaker on for awhile before you turn on the power it has something to do with electrolytic capacitors. You are reforming the capacitors by letting it sit with power on. Then it works fine.

Thank you for the suggestions. I checked the DC power supply with oscope and it was fine. I tried a different 24V power supply just in case and nothing changed.
During testing I noticed something interesting. There is a DC circuit board in the enclosure that controls all the outputs. Every output has a corresponding LED, that is activated when the circuit is live. You can see which outputs are active by just looking at the LED´s and checking it from the electric diagram. During a cold start all the LED`s are slightly on. After some time passes the LED`s start to dim and finally when they are completely off, machine becomes operational. I took the DC board out and tested it on a bench. The board was working flawlessly. Seems like this anomaly is coming from the Fanuc side. Fanuc is giving some current to every output when the internal capacitors are not yet fully charged. As temperature is getting colder here in my workshop this problem is getting worse. Today it took solid 30-40 minutes to get the machine going. Maybe the issue is the Fanucs power supply? What should I test next? Thank you for you support so far!

 

[sander96]

Update. Fanuc is not very keen to give info, but through some personal contacts I managed to get an answer from Fanuc Sweden. They suggested that this is probably some thermal issue of Fanuc power supply PCB and the board needs to be replaced/fixed.