Actualizacion EMCO VCM 300

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ashesman
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Re: Actualizacion EMCO VCM 300

Post by ashesman »

If your VFD has two encoder inputs then use both. If it has only one then you need to use the spindle encoder.

Due to the gear ratio, to do orientation, you need to measure at the spindle shaft. There could be multiple turns or part turns of the motor to the spindle so stopping the motor in a fixed place will result in the spindle stopping in the correct place only some of the time.
Oscar6
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Re: Actualizacion EMCO VCM 300

Post by Oscar6 »

Well let's start, this weekend I have done some tests, I have configured the inverter to try to make quick stops and I have not managed to make them very fast, the dc bus voltage I have set to the maximum 900V, braking at 100% and braking time 1 second, with the engine at 6000 rpm braking from the beginning it gives a high dc bus voltage error, the engine is only capable of braking very quickly below 1500 rpm, when braking at 3000 rpm the braking is executed several times until it brakes In acceleration, there is no problem, it seems that from 0 to 6000 rpm it rises quickly in 2 seconds or so, I don't know something, I'll be doing wrong, I'll read the variator manual a little more to see if something escapes me but I don't know. I have also checked the motor and spindle pulleys and they do not have teeth, they are very difficult to measure in the place they are, what I have done has been to measure in degrees of the spindle per turn of the motor with an angle tool, what happens that is not 100% exact, there may be an error of a few hundredths or thousandths, calculating the average of 20 measurements the result has been (1.413: 1 or 0.707: 1) the small pulley is on the motor and the large one on the spindle. The spindle encoder I have not had time to locate the cables to do the tests will be for next week. Another question I have with the x, y, z axis controllers, the machine is now powered with 3 phases 380V 1 ground, what would be the best voltage option for the axis drivers, I have two options, a three phase driver 380v, or 220v single phase and neutral drivers, could feed the machine with 3 phases 380 1 neutral 1 ground, the 220v would take them out of each phase of 380v and neutral they think it would be a good idea, which they recommend. Thank you
martyscncgarage
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Location: Mesa, AZ

Re: Actualizacion EMCO VCM 300

Post by martyscncgarage »

Oscar6 wrote: Mon Aug 02, 2021 8:25 am Well let's start, this weekend I have done some tests, I have configured the inverter to try to make quick stops and I have not managed to make them very fast, the dc bus voltage I have set to the maximum 900V, braking at 100% and braking time 1 second, with the engine at 6000 rpm braking from the beginning it gives a high dc bus voltage error, the engine is only capable of braking very quickly below 1500 rpm, when braking at 3000 rpm the braking is executed several times until it brakes In acceleration, there is no problem, it seems that from 0 to 6000 rpm it rises quickly in 2 seconds or so, I don't know something, I'll be doing wrong, I'll read the variator manual a little more to see if something escapes me but I don't know. I have also checked the motor and spindle pulleys and they do not have teeth, they are very difficult to measure in the place they are, what I have done has been to measure in degrees of the spindle per turn of the motor with an angle tool, what happens that is not 100% exact, there may be an error of a few hundredths or thousandths, calculating the average of 20 measurements the result has been (1.413: 1 or 0.707: 1) the small pulley is on the motor and the large one on the spindle. The spindle encoder I have not had time to locate the cables to do the tests will be for next week. Another question I have with the x, y, z axis controllers, the machine is now powered with 3 phases 380V 1 ground, what would be the best voltage option for the axis drivers, I have two options, a three phase driver 380v, or 220v single phase and neutral drivers, could feed the machine with 3 phases 380 1 neutral 1 ground, the 220v would take them out of each phase of 380v and neutral they think it would be a good idea, which they recommend. Thank you
Did you purchase a BRAKING RESISTOR for your Variable Frequency Drive? No resistor the VFD has no where to dump the energy and will fault.
1 second stop seems unreasonable to me, especially if you have a large tool in the spindle. 2-3 seconds is usually where I set it.

Marty
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
ashesman
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Re: Actualizacion EMCO VCM 300

Post by ashesman »

You need a braking resistor or dc bus stabilizer to achieve high speed deceleration. I run 300ms to 6000 rpm and the same to stop but that's with a small motor.

Even a few seconds might be a big ask without a resistor. Maybe there is one on the old drive you could use. Bit it will meed to be the right resistance and power rating as per the VFD manual.

For the axis drives, the power supply you will need depends on the motors voltage rating. The output voltage of a servo drive is roughly the same as its input voltage. Try run the servo drives on three phase if possible. Single phase will be 1.7 times higher input current and will mean you will need to over rate the drives by that much.

You will need to set up the spindle encoder for sure to do orient with that gear ratio.
Oscar6
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Re: Actualizacion EMCO VCM 300

Post by Oscar6 »

martyscncgarage wrote: Mon Aug 02, 2021 9:28 am
Oscar6 wrote: Mon Aug 02, 2021 8:25 am Well let's start, this weekend I have done some tests, I have configured the inverter to try to make quick stops and I have not managed to make them very fast, the dc bus voltage I have set to the maximum 900V, braking at 100% and braking time 1 second, with the engine at 6000 rpm braking from the beginning it gives a high dc bus voltage error, the engine is only capable of braking very quickly below 1500 rpm, when braking at 3000 rpm the braking is executed several times until it brakes In acceleration, there is no problem, it seems that from 0 to 6000 rpm it rises quickly in 2 seconds or so, I don't know something, I'll be doing wrong, I'll read the variator manual a little more to see if something escapes me but I don't know. I have also checked the motor and spindle pulleys and they do not have teeth, they are very difficult to measure in the place they are, what I have done has been to measure in degrees of the spindle per turn of the motor with an angle tool, what happens that is not 100% exact, there may be an error of a few hundredths or thousandths, calculating the average of 20 measurements the result has been (1.413: 1 or 0.707: 1) the small pulley is on the motor and the large one on the spindle. The spindle encoder I have not had time to locate the cables to do the tests will be for next week. Another question I have with the x, y, z axis controllers, the machine is now powered with 3 phases 380V 1 ground, what would be the best voltage option for the axis drivers, I have two options, a three phase driver 380v, or 220v single phase and neutral drivers, could feed the machine with 3 phases 380 1 neutral 1 ground, the 220v would take them out of each phase of 380v and neutral they think it would be a good idea, which they recommend. Thank you
Did you purchase a BRAKING RESISTOR for your Variable Frequency Drive? No resistor the VFD has no where to dump the energy and will fault.
1 second stop seems unreasonable to me, especially if you have a large tool in the spindle. 2-3 seconds is usually where I set it.

Marty
Hi, it is clear that a braking resistor is needed to brake faster, I still do not have it, but I do not know if I need that much brake for a hobby machine, for now I will use 2 or 3 seconds as you say Marty to do tests, I will leave pending the braking resistor that can be fitted in the future, thanks
Oscar6
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Re: Actualizacion EMCO VCM 300

Post by Oscar6 »

ashesman wrote: Mon Aug 02, 2021 3:17 pm You need a braking resistor or dc bus stabilizer to achieve high speed deceleration. I run 300ms to 6000 rpm and the same to stop but that's with a small motor.

Even a few seconds might be a big ask without a resistor. Maybe there is one on the old drive you could use. Bit it will meed to be the right resistance and power rating as per the VFD manual.

For the axis drives, the power supply you will need depends on the motors voltage rating. The output voltage of a servo drive is roughly the same as its input voltage. Try run the servo drives on three phase if possible. Single phase will be 1.7 times higher input current and will mean you will need to over rate the drives by that much.

You will need to set up the spindle encoder for sure to do orient with that gear ratio.
Hi, the motors that I have I think I cannot use them with delta motor units, the delta units use their own encoders and are not compatible with my motors, I was thinking of changing the motors and controllers, but I don't know if I could use these motors with some compatible controller With the OAK centroid board, the motor mounts a 1000 pulse a, b, z encoder. But I also have 3 options I don't know which one will be better:
1: 1 three-phase delta 380 controller and 1kw motor for z, 2 three-phase delta 380 controllers and 750w motor for x, y, and connect it to the 380v three-phase network directly. Blue circle image
2: 1 delta 220 three-phase controller and 1kw motor for the z, 2 delta 220 three-phase controllers and 750w motor for x, y, and connect it to the internal 380/220 transformer of the machine, I put a photo of the original scheme and red circle where I would connect the controller, it could be correct or it is not worth taking advantage of this three-phase 220v installation.
3: 1 single-phase delta 220 controller and 1kw motor for the z, 2 single-phase delta 220 controllers and 750w motor for x, y, and connect it to the three-phase network between neutral terminal and 380 phase. Green circle image
transformaador 220v.jpg
ashesman
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Re: Actualizacion EMCO VCM 300

Post by ashesman »

I just spent eight months battling with servo motors and drives. There is no eneral purpose servo drive available that is cost effective. All the lower cost options are motor and drive pairs with proprietary encoders. Like delta and DMM.

I would go with three phase drives. If you go single phase you will need 1.7kW drives for 1kW motors due to the increase in input current. They will have high input current spikes which create electrical noise and require larger cables. Three phase drives will also keep your phases more balanced.

As to 400V or 200V drives, that's up to you. 400V drives will have lower current requirements so can have smaller cables and circuit protection and filters. But may be more expensive.

You could choose to remove the transformer all together and just run everything from 400V.

1000 PPR encoders are quite low resolution. That's 4000 counts per revolution. Depending on the pitch of your lead screws will determine that control resolution. Modern motors are upwards of 65535 counts per revolution.

The final result will be the same either way.
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Re: Actualizacion EMCO VCM 300

Post by Oscar6 »

Hello again, thanks for the help in these doubts that are coming up, I will study the 380v three-phase units as you say, although I did not want to spend so much money on a machine that will work very little, if one day it were to work at least 50 % would be enough, to do some mechanical work on a small racing car for example lowering a cylinder head, making a combustion chamber, etc, almost always in aluminum, I think something could be achieved, it would take me a while to save the money For the missing things, in the meantime I will be studying the units and adjusting the electrical installation of the machine. Thanks again.
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Re: Actualizacion EMCO VCM 300

Post by ashesman »

If you want to save some money, look at the chinese motor and servo drive combinations from aliexpress. Or DMM drives and motors.

I tried my best to do my conversion on a budget and am probably well over $10000 USD. All the little parts add up.
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Re: Actualizacion EMCO VCM 300

Post by Oscar6 »

Hello again, this weekend I have been able to dedicate a couple of hours to this project, I have managed to position the tool using the encoder of the spindle shaft and it seems to be going well, although the drive manual does not recommend this configuration for not driving very Well the motors, the manual recommends using the A and B signals of the motor and the Z phase of the spindle axis, I tried this configuration but I did not get a good orientation, for now I will leave it in the configuration that works to see what happens. I am going to try to make a small description of how the tool change works. What do you think?
At the beginning of this topic there is a video that shows how the tool changes are made, it consists of a 12-tool drum that is moved by the same spindle motor, there are two Z limit switches, one to know when the tool is in working position and another when the spindle is engaged with the drum in the highest part, then it has 3 inductive sensors that I think, one to mark tool # 1, two to detect each tool step, three I'm not sure but I think it calculates the degrees of movement of the drum. I have manually calculated and tested that the spindle axis has to make exactly two turns for each tool change. The operation is very simple, first the spindle is raised to a safety height, second the tool is positioned, third the spindle is raised to the highest limit switch to engage the motor with the drum, fourth the spindle is rotated as many turns are necessary for the chosen tool, at this moment the spindle is already oriented, fifth the spindle goes back down to the end of the work position stroke and so it seems that everything works correctly, I have done the whole process manually and it seems to work all at very slow speeds and moving the z-axis by hand. One of the doubts that I have when it comes time to program the plc, is whether the OKA board will be able to control the motor to give the exact turns of the drum and if it will do it using only the encoder or it will also have to use the inductive sensors, but that is it will be for the end when everything else is working. Thanks
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