we have a pick and place setup that consists of a Y-axis mast that moves back and forth on a horizontal carriage x-axis.
The mast hangs on, and is moved up and down, and back and forth by means of a cogged belt that is routed on the pullies of two servo motors controlled by Kinetix drives and a control Logix PLC
The motors both turning in the same direction will move it in the horizontal, and the same two motors turning in opposite directions will move it up and down.
This whole setup has been operating for probably 15 years but lately when the mast is moved to near the end of the x-axis ,and then down the y- axis ( a place ) it "shudders" as if something mechanical is causing it...
After rebuilding and adjusting this thing about three times over the past week, I am completely convinced there is nothing mechanical beyond the motors' gearboxes causing this. And it only happens intermittently during the "place" move.
We get no errors on the Kinetix drives and the motors have to turn pretty precisely to move the thing straight up and down. I can't help but thinking that a problem in one motor's gearbox would cause the mast to move at least partially sideways as well as straight up and down.
It seems to me that the shuddering should in itself be enough to cause some sort of error on the Kinetix, and I can't imagine the PLC giving the Kinetix some command that would cause it to run correctly one time, and shudder the next.
I hope someone has an idea... thanks
I wanted to add, that there are brakes on these motors, but I do not think they are employed during any of the "moves", and the shuddering occurs when the motors would have to exert some sort of force on the mast to keep it from falling by gravity. there is a pick move on the other end of the carriage that also would fall by gravity, but it doesn't go as low.
It is hard for me to understand how a motor would hold a weight from falling by gravity while allowing it to descend at a controlled speed. It probably takes about 20 - 25 pounds to hold this thing up.
I am convinced there is nothing mechanical beyond the motors' gearboxes causing this .
The mast hangs on, and is moved up and down, and back and forth by means of a cogged belt that is routed on the pullies of two servo motors controlled by Kinetix drives and a control Logix PLC
The motors both turning in the same direction will move it in the horizontal, and the same two motors turning in opposite directions will move it up and down.
This whole setup has been operating for probably 15 years but lately when the mast is moved to near the end of the x-axis ,and then down the y- axis ( a place ) it "shudders" as if something mechanical is causing it...
After rebuilding and adjusting this thing about three times over the past week, I am completely convinced there is nothing mechanical beyond the motors' gearboxes causing this. And it only happens intermittently during the "place" move.
We get no errors on the Kinetix drives and the motors have to turn pretty precisely to move the thing straight up and down. I can't help but thinking that a problem in one motor's gearbox would cause the mast to move at least partially sideways as well as straight up and down.
It seems to me that the shuddering should in itself be enough to cause some sort of error on the Kinetix, and I can't imagine the PLC giving the Kinetix some command that would cause it to run correctly one time, and shudder the next.
I hope someone has an idea... thanks
I wanted to add, that there are brakes on these motors, but I do not think they are employed during any of the "moves", and the shuddering occurs when the motors would have to exert some sort of force on the mast to keep it from falling by gravity. there is a pick move on the other end of the carriage that also would fall by gravity, but it doesn't go as low.
It is hard for me to understand how a motor would hold a weight from falling by gravity while allowing it to descend at a controlled speed. It probably takes about 20 - 25 pounds to hold this thing up.
I am convinced there is nothing mechanical beyond the motors' gearboxes causing this .
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