Axis AX-906 Podręcznik Użytkownika Pobierz pdf (Strona 22)

78

AX

DRIVE USER GUIDE

Gauging

Motor

Resonance

TACHOMETER

METHOD

SOUNDING

BOARD METHOD

STETHOSCOPE

METHOD

TOUCH METHOD

Locate

the

natural

frequency

of

the System

STEP 1

STEP 2

Selecting a

method

of gauging

motor

resonance

can

be

accomplished

in

a

number

of ways;

Using

an

oscilloscope to look

at

the

output

of

a

tachometer

attached

to

the

motor

shaft. The

tachometer

will

output

a

DC

voltage,

proportional

to

speed.

This

voltage will oscillate

around

an

average voltage

when

the

motor

is

resonating. The

amplitude

of

this

oscillation will

be

at

a

maximum

when

the

natural

frequency of

the

motor

is

located. USing

this

method

your

goal

is

to

tune

for

the

lowest oscillation amplitude.

When

practicing

your

tuning

skills,

an

unloaded

motor

can

be

placed

on

a

sounding

board

or

a table.

When

a velocity is

commanded

which

is

near

the

motors

natural

frequency,

the

phenomenon

will

cause

Vibration

which

will

become

audible.

Using

this

method

your

goals is to

tune

for

the

lease

amount

of

vibration.

When

tuning

under

loaded conditions

the

audible

vibration

caused

by

the

motors

natural

frequency

can

be

heard

by

placing

the

tip

of

a screw drive

against

the

motor

casing

and

holding

the

handle

of

the

screw driver close to

your

ear

(as you

would a stethoscope).

This

will also allow you

to

hear

the

different

magnitudes

of vibration

caused

by

the

motors

natural

frequency. USing

this

method

your

goal is to

tune

for

the

least

amount

of Vibration.

After some experience with

tuning,

it

is

possible to locate a

motor's

natural

frequency

by

simply placing

your

fingertips

on

the

motor

shaft

and

adjusting

the

motor

velocity. Once

the

Critical velocity is located,

tuning

for

maximum

smoothness

can

be

done

in

the

same

way.

CAUTION

Exercise extreme caution whenever

you

are

near

any

moving

part

of

a mechan1cal system. Also, be

wary

of

touching

the

motor, as

it

is

very

hot

during

normal

operating conditions.

To

tune

the

drive you will

need

a small non-conductive screw

driver.

Before you

can

tune

the

drive to

its

motor,

you

will

need

to

locate

the

natural

frequency

of

the

motor

and

its

load. This

can

be

accomplished

using

the

following procedure:

Let

the

motor

and

driver

wann

up

for

30

minutes

to

an

hour.

Locate

the

tuning

pots

on

the

drive you

are

uSing. Figure 4-5

below

shows

the

location of

the

AX

Drive

tuning

pots. Note

that

the

small

metal

plate held

in

place with two

screws

must

be

removed to reveal

the

tuning

pots.

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