drive design for grinding machine

[max.carl55]

Hello everyone,

I would like to choose a motor with the right power for the X-feed (table) of a grinding machine.
I choose a servo motor with a ball screw as the drive.
My table should reach a speed of 40m/min.

Can someone help me with a simple calculation to determine the required force or torque/power so that I can choose the correct motor.

Suitable literature would of course be fantastic.
My task is not focussed on a detailed electrical calculation. It should be as simple as possible so that I can make an estimate for the correct servo motor.


Thank you in any case!

Best regards

Max

 

[3DDave]

My thought:

Power = force X velocity; since the table force = grinding wheel force then Power/velocity = whatever that force is.

The ratio of the grinding motor to the table drive motor is roughly the ratio of the grinding wheel edge speed to the expected table speed.

If the table has too much power it can force material too fast and the grinding motor will stall. If the grinding wheel has too much power, it cannot be used as the table cannot feed material fast enough.

 

[MintJulep]

40m/min

What are you grinding at this speed?

 

[TugboatEng]

I would size the feed motor to be able to stall the grinder motor. You already know the grinder motor torque. Divide that by the wheel diameter and now you have your max table force. Multiply this by the table speed and that is your required feed power.

Which limitation would you rather have occur first? Do you want your table feed to limit production from your big expensive spindle motor?

 

[dvd]

In addition to previous advice indicated, I would also pile on any linear way cover resistance forces, preloaded linear way forces, and frictional resistance of grinding table plus loading from workpiece, and maybe acceleration forces depending on how quickly you accelerate and/or change directions.

 

[BEMPE16524]

What are you grinding at this speed?

wondering the same.

 

[jassco]

That is a crazy speed for surface or cylindrical grinders. It sounds like a rocket (LOL).

 

[Compositepro]

The high table speed would be for initial positioning of the work piece under no load, I imagine. The above comments are correct for the grinding operation.

 

[tygerdawg]

As others stated, the process parameters of 40m/min seems...fast.

For sizing, you must identify, quantify, and sum all of the torques to identify the peak torque (due to force, due to inertia, translational and rotational). This is the minimum that the motor must deliver at the design RPM. This analysis is not trivial. Websearch for the Smart Motion Cheat Sheet pdf for a good overall summary of the various analyses needed. Beyond that, most gearmotor manufacturers have some form of applications engineering section in their catalogs or other documents that go into more extreme detail about motion control and motor sizing.

And remember: torque is cheap, so be sure to use plenty of it.

 

[CWB1]

Machinery's Handbook is an excellent reference for cutting/grinding forces and thereby tool/machine design.

Depending on the positional accuracy needed, you may be able to use a simpler, more durable design than servos and ball screws. Most 3-axis surface grinders for example use a simple rack&pinion table feed bc the only accuracy needed is positioning the wheel height.