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IndustryArena Forum > MetalWorking Machines > Okuma > Okuma LB15 spindle motor problem
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  1. #1
    Join Date
    Mar 2005
    Posts
    10

    Okuma LB15 spindle motor problem

    Hi guys. My shop was flooded few months ago with 20 inches of water. Spindle motors and a lot of electronics on my Okumas were under water. No flood insurance.
    Short story , I have two machines that still not running.
    On old Okuma Lathe LB15 (A06B-6044-H018 spindle drive A20B-1000-069 top board , A06B-1008-B902 spindle motor) I have an alarm 110 ALARM-A SDU 1.
    On spindle drive it's Alarm 2 (Excessive speed deviation). I get those alarms when I try to run spindle. It makes about 1 revolution and it stops resulting in alarm. No alarm when rotating slowly with JOG button on control. In first repair place they changed bearings and baked motor for 1000$. After instalation on machine having those alarms I gave it second repair place. They said that speed sensor needs to be replaced. After 2 months they couldn't get the replacement part I took it to third repair facility wher they had all parts available. They checked the motor and surprisingly they said it runs perfectly. I took it back and connected all wires to machine without installing it on machine for testing. Still get alarms. An attached pictures you can see it.
    My questions are:
    -Does a motor has to be installed on machine (run spindle and opticoder) in order to test it ? Or can it be like on the picture?
    -When they tested motor in third place they had cables X, Y, Z bolted (connected)together. Why did they do it? If I try to run like that what will happen?
    - Any idea what could be wrong?
    Thank you for any suggestions.
    Attached Thumbnails Attached Thumbnails Picture 029.jpg   Picture 030.jpg   Picture 031.jpg  

  2. #2
    Join Date
    Mar 2009
    Posts
    1992
    check IGBT modules of frequency inverter. Motor must rotate the encoder for proper test. Wiring depends on test method and expected result. Three - phase motors are winded by three windings, so you have 6 wire ends. For "star" connection three ends are connected to neutral or just together

  3. #3
    Join Date
    Feb 2009
    Posts
    6028
    Well I've actually been through something very similar at a customers shop years ago, on the same machine. He used a pressure washer however.

    To make a very long painful story short, you have a fanuc motor and drive in that machine. Don't go through okuma at all on those! (3 bad drives later) call fanuc in directly. They fixed my customers on site, in about 30 minutes. Your drive unit is probably blown up if you tried to start it before getting the motor baked.

  4. #4
    Join Date
    Mar 2005
    Posts
    10
    Thank you for replying to my post. They checked my drive and it's OK , but I am still getting an alarm #2. Now my suspicion is on motor connection. As you see on attached picture (it was taken when I got it back from initial repair) Blue wires are on U and Red wires are on W. It wasn't like that before repair becouse I took pictures. I asked a guy why he switched those wires and he said he might made a mistake. Is it possible that he switched wires inside motor and after assembling it he realized he made a mistake and than simply switched wires inside connection box ? Now my wires are how they were before repair. Would that trip #2 alarm on spindle drive ? Would I damage anything if I switch wires back between W and U just to see if that's a problem ?
    Attached Thumbnails Attached Thumbnails Picture 003.jpg  

  5. #5
    Join Date
    Feb 2009
    Posts
    6028
    That would make the motor spin backwards, so yes it could give you that alarm. Just three phase...

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