3 phase motorchoice...

I have a little project, designing a sawing machine...

Problem is, I don't know what motor I should use.

I have calculated that I need 2,286 N (Torque) (each tooth)

I have calculated a speed of 485 rad/s. (axe running 4620 rpm)

So I calculated the Power that I need: P = W x T = 485 x 2,286 N = 1109 W

I know that the diameter of the saw is 165mm (= d2)
I know that n = 4620 rpm.

n1/n2 = d1/d2

so I choose a motor of 1,5kW and a speed of 3000 rpm.

d1 = (n1 x d2) / n2 = (3000 x 0,165m)/4620 = 107 mm (diameter on the motorside).

What I don't understand is, I've calculated a needed power of 1,1 kW and chosen a motor of 1,5kW, but if I choose a motor of 1,5 kW that has 1400 rpm or one with 3000 rpm, I know that it needs 1,1 kW to make it work on the saw side, but the motor does not has to be 1,1kW, can be less or more, depending on the diameters that are calculated, or am I wrong ?

What motor is best for a sawing machine... a standard 1400 rpm 1,5kW motor, or one with 3000 rpm ?

Is this a circular saw application ?

We need a picture please - how is the motor connected to the blade, what is the duty cyce, how about an allowance for friction between the blade and the material being cut.

You have some fundamental problems.

First, horsepower is horsepower everywhere in the system, and if you change speed the torque will change but the horsepower remains constant.

Second, As I recall my metric Newton is force, and Newton-meter is torque. Therefore, your calculations can't be correct.

hi

I wrote N, should have been Nm

• Hoeksnelheid (W):

v = s / t



s = π * d = 1 tr



v = π * d * n



De gewenste snijsnelheid = 40 m/s



Zaagblad ø = 165 mm of 0,165 m



40 m/s = π * 0,165m * n



n = 40 / (π * 0,165 m) = 77,22 omw/s => *60 = 4620 omw/min



W = 2 * π * n = 2 * π * 77,22 omw/s = 485 rad/s

• Koppel (T):

Fx => cos 30º = Fx / 32 N => Fx = 32 N * cos 30º = 27,71 N



Fy => sin 30º = Fy / 32 N => Fy = 32 N * sin 30º = 16 N



De loodrechte Fy zal geen moment veroorzaken =>



T = F * a => T = Fx * a => T = 27,71 N * 0,165/2 = 2,286 Nm


The horsepower remains constant, okay, thanks

Tom Jenkins said:

You have some fundamental problems.

First, horsepower is horsepower everywhere in the system, and if you change speed the torque will change but the horsepower remains constant.

Second, As I recall my metric Newton is force, and Newton-meter is torque. Therefore, your calculations can't be correct.

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