Kistler 9236A1 Owner's manual

Instruction

Manual

Ceramic-

Microvibration

Dynamometer

Type 9236A…

9236A_002-883e-12.19

Foreword

9236A_002-883d-12.19 Page 1

Foreword

Thank you for choosing a Kistler quality product charac-

terized by technical innovation, precision and long life.

Information in this document is subject to change without

notice. Kistler reserves the right to change or improve its

products and make changes in the content without obli-

gation to notify any person or organization of such

changes or improvements.

ed by various intellectual property rights. For more details

visit www.kistler.com. The Kistler Group includes Kistler

Holding AG and all its subsidiaries in Europe, Asia, the

Americas and Australia.

Kistler Group

Eulachstraße 22

8408 Winterthur

Switzerland

Tel. +41 52 224 11 11

[email protected]

www.kistler.com

Ceramic-Microvibration Dynamometer Type 9236A…

Page 2 9236A_002-883d-12.19

Inhaltsverzeichnis

1.Introduction .................................................................................................................................. 3

2.Important information ................................................................................................................. 4

2.1For your safety .................................................................................................................... 4

2.2How to treat the instrument ................................................................................................. 5

2.3Tips for using the instruction manual .................................................................................. 6

2.4What happens after modifications? ..................................................................................... 6

2.5Disposal instructions for electrical and electronic equipment ............................................. 6

3.General description of the instrument ...................................................................................... 7

3.1What does a multicomponent dynamometer do? ............................................................... 7

3.2Functional principle ............................................................................................................. 8

3.3Design of the dynamometer ................................................................................................ 9

4.Assembly, installation and putting into operation ................................................................. 10

4.1Important remarks ............................................................................................................. 10

4.2Assembling the dynamometer........................................................................................... 10

4.3Positioning of the dynamometer ....................................................................................... 11

4.4Basic circuitry and cabling of the measuring system ........................................................ 12

4.4.1Force measuring with 3 components (Fx, Fy, Fz) .............................................................. 13

4.4.23-component force measurement ..................................................................................... 14

4.4.3Force and moment measuring with 6-components (Fx, Fy, Fz, Mx, My, Mz) ...................... 15

5.Operation .................................................................................................................................... 17

5.1Range selection ................................................................................................................ 17

5.2Measuring small force changes ........................................................................................ 17

5.3Usable frequency range .................................................................................................... 19

5.4Temperature influences .................................................................................................... 21

5.5Polarity of the measuring signal ........................................................................................ 21

6.Maintenance ............................................................................................................................... 22

6.1Recalibrating the instrument ............................................................................................. 22

6.2Maintenance tasks ............................................................................................................ 23

7.Trouble shooting ....................................................................................................................... 24

7.1Tracing faults and remedying them ................................................................................... 24

7.2Defective dynamometer .................................................................................................... 25

8.Technical data............................................................................................................................ 26

8.1Accessories ....................................................................................................................... 26

9.Annex .......................................................................................................................................... 27

9.1Glossary ............................................................................................................................ 27

9.2Measurement Uncertainty ................................................................................................. 31

9.3Linearity ............................................................................................................................. 32

9.4Frequency range ............................................................................................................... 34

9.5Influence of Temperature .................................................................................................. 35

Introduction

9236A_002-883d-12.19 Page 3

1. Introduction

Please take the time to thoroughly read this instruction

manual. It will help you with the installation, maintenance,

and use of this product.

To the extent permitted by law Kistler does not accept

any liability if this instruction manual is not followed or

products other than those listed under Accessories are

used.

Kistler offers a wide range of products for use in measur-

ing technology:

 Piezoelectric sensors for measuring force, torque,

strain, pressure, acceleration, shock, vibration and

acoustic-emission

 Strain gage sensor systems for measuring force and

torque

 Piezoresistive pressure sensors and transmitters

 Signal conditioners, indicators and calibrators

 Electronic control and monitoring systems as well as

software for specific measurement applications

 Data transmission modules (telemetry)

Kistler also develops and produces measuring solutions

for the application fields engines, vehicles, manufac-

turing, plastics and biomechanics sectors.

Our product and application brochures will provide you

with an overview of our product range. Detailed data

sheets are available for almost all products.

If you need additional help beyond what can be found ei-

ther on-line or in this manual, please contact Kistler's ex-

tensive support organization.

Ceramic-Microvibration Dynamometer Type 9236A…

Page 4 9236A_002-883d-12.19

2. Important information

2.1 For your safety

 This instrument has been tested thoroughly and it left

the works in a perfectly safe condition. To maintain

this condition and assure safe operation, the user

must observe the directives and warnings contained

in these instructions

 The dynamometer must be installed, operated and

maintained only by persons who are familiar with it

and adequately qualified for their particular tasks

 When it must be assumed that safe operation is no

longer possible, the instrument must be taken out of

operation and secured against unintentional use.

It must be assumed that safe operation is no longer

possible if:

 the instrument is visibly damaged,

 it no longer functions,

 it has been in lengthy storage under adverse

conditions,

 it has received rough treatment during transport

Important!

Fix the dynamometer according to the instructions. See

section 4.2: Assembling the Dynamometer, for details.

Important!

Fix all parts mounted on the top plate of the dynamome-

ter according to the forces expected!

Important information

9236A_002-883d-12.19 Page 5

2.2 How to treat the instrument

The dynamometer may be used only under the specified

environmental and operating conditions

 The insulation resistance is crucially important with

piezoelectric measurements. It must be around 1014

 (but at least 1013 )

 To obtain this resistance, all plug and socket connec-

tions must be kept meticulously clean and dry

 The insulation resistance can be measured with the

insulation tester Type 5493

 Protect the signal output against dirt and do not touch

it with your fingers. When the connection is not being

used, cover it with the cap provided

 The connecting cable from dynamometer to charge

amplifier is highly insulating. Use only the proper

cable

 Do not remove the connecting cable from the dyna-

mometer

 When the dynamometer is not in use, protect it by

keeping it in the packing case supplied

 When performing long-time measurements, make

sure that the temperature of the dynamometer re-

mains as constant as possible

Ceramic-Microvibration Dynamometer Type 9236A…

Page 6 9236A_002-883d-12.19

2.3 Tips for using the instruction manual

We recommend reading the entire Instruction Manual as

a matter of principle. If you're in a hurry, however, and

you've already gathered experience with Kistler dynamo-

meters, you can confine your reading to the information

that you really need (see section 4).

We have endeavoured to arrange these instructions so

that you can find the information you need without diffi-

culty.

Please keep this Instruction Manual in a safe place

where they can be consulted any time.

If the instructions get lost, just turn to your Kistler cus-

tomer service station and they will be replaced without

delay.

All information and directives in these instructions may be

modified at any time without prior notification.

2.4 What happens after modifications?

Modifications to instruments result in alterations of the

operating instructions as a rule. In such cases, enquire at

your Kistler customer service station about the possibili-

ties of updating your documentation.

2.5 Disposal instructions for electrical and electronic equipment

Do not discard old electronic instruments in municipal

trash. For disposal at end of life, please return this

product to an authorized local electronic waste dispos-

al service or contact the nearest Kistler Instrument

sales office for return instructions.

General description of the instrument

9236A_002-883d-12.19 Page 7

3. General description of the instrument

3.1 What does a multicomponent dynamometer do?

The multicomponent dynamometer provides dynamic and

quasi-static measurement of the 3 orthogonal compo-

nents of a force (Fx, Fy, Fz) acting from any direction onto

the top plate.

With the aid of optional evaluation devices the 3 mo-

ments Mx, My and Mz can be measured as well (see sec-

tion 4.4.3).

The dynamometer has high rigidity and hence high natu-

ral frequency. The high resolution enables very small dy-

namic changes to be measured in large forces.

The dynamometer measures the active cutting force

regardless of its application point. The usable frequency

range depends mainly on the resonance frequency of the

entire measuring rig.

.

Fig. 1: Dynamometer Typ 9236A

Most important applications for the multicomponent dy-

namometer are:

 Measurements in the vacuum chamber

 Measurements in the clean room

 Microvibration measurements

 Satellite testing

Ceramic-Microvibration Dynamometer Type 9236A…

Page 8 9236A_002-883d-12.19

3.2 Functional principle

The force to be measured is introduced via a top plate

and distributed between four piezoelectric 3-component

force sensors arranged between the base and top plates.

Each of the sensors has three pairs of quartz plates, one

sensitive to pressure in the z direction and the other two

to shear in the x and y directions respectively. The

measure ment is virtually without displacement.

In these four force sensors the force introduced is broken

down into three components.

Fig. 1: Function principle

For the force measurement in 3 components the individ-

ual signals are led together in the connecting cable.

For force and moment measuring with 6 components, all

8 individual signals are led via the connecting cable

straight to the charge amplifiers.

Depending on the direction of the force, positive or nega-

tive charges occur at the connections. Negative charges

give positive voltages at the output of the charge amplifi-

er, and vice versa.

.

General description of the instrument

9236A_002-883d-12.19 Page 9

3.3 Design of the dynamometer

The dynamometer consists of four 3-component force sen-

sors sandwiched under high preload between a baseplate

and a top plate. This preload is needed to transmit the

friction forces.

Fig. 2: Schematic design of the dynamometer

The four force sensors are mounted ground-insulated.

Ground loop problems are largely eliminated in conse-

quence.

The dynamometer has an especially high natural fre-

quency and is particularly suitable for use in clean rooms

and vacuum chambers. Together with well shielded ca-

bles and high-quality charge amplifiers (see data sheet)

an extraordinarily low-noise measuring chain can be set

up.

1 Force senso

r

2 Base plate

3 Top plate

4 Connector

5 Cap

Ceramic-Microvibration Dynamometer Type 9236A…

Page 10 9236A_002-883d-12.19

4. Assembly, installation and putting into operation

4.1 Important remarks

The multicomponent dynamometer Type 9236A is a pre-

cision instrument, but its inherent accuracy can be ex-

ploited and retained only if it is treated with care. The fol-

lowing rules should therefore be noted:

 Mount the dynamometer on a vibration-isolated base,

which is as stiff as possible (e.g. granite table with 10

times the mass), and only use the highest quality ca-

bles and charge amplifiers (Type 5080A). If the Type

9236A is mounted on a soft, cushioning underlay such

as foam, its natural frequency changes dramatically

and the measurements can be strongly distorted.

 Never drop the dynamometer or expose it to heavy

impacts! The maximum force of a shock of this kind

could exceed the measuring range of the instrument

and cause permanent deformations

 Never use a hammer to position the workpieces, as

such blows might also cause deformation!

On the following pages you will find directions for installing

the dynamometer and basic data for designing the measur-

ing facility.

4.2 Assembling the dynamometer

The following directions must be observed if the dy-

namometer is to be mounted properly:

 The dynamometer must be installed only by persons

who are familiar with it and sufficiently qualified for

this work

 First the connecting cable has to be mounted. Both

connector sides (dynamometer and cable) have to be

cleaned with Kistler cleansing and insulating spray

Type 1003. To seal the connector the O-Ring is used

(scope of delivery). The mounting surface for the

O-Ring must be clean. The O-Ring is placed properly

and the flange of the cable is mounted onto the

dynamometer by means of two screws (M4x10) and

tightened

Tightening moment = 4,5 N·m

 Before mounting the dynamometer on a testing de-

vice, make sure that the mounting surface is perfectly

flat. Uneven supporting surfaces will cause internal

stresses, which may expose the individual force sen-

sors to severe additional shear stressing and cause in-

creased crosstalk

Assembly, installation and putting into operation

9236A_002-883d-12.19 Page 11

 The bottom surface of the dynamometer is ground,

i.e. fine-machined. The instrument should therefore

be mounted on ground or equivalently machined sup-

porting surfaces

 Clean the contact surfaces thoroughly before mount-

ing

 To align the Dynamometer on the machine table one

of the side wall of the flange can be used

 Make sure that the dynamometer rests absolutely

flat. Even the smallest air gap will cause undesirable

elasticity and reduce the resonant frequency of the

measuring rig. All mountings must therefore be con-

sidered from the vibration aspect also

Procedure:

 Remove the four covers (pos. 5 in Fig. 3) on the dy-

namometer cover plate.

 To lift and position the dynamometer, the ring bolts

and washers supplied can be screwed in here.

 Tighten the dynamometer with the four supplied

M12x35 screws (strength class 12.9) through the

cover plate.

 The Type 9236A2 can also be fixed in the centre with

the supplied M12x50 screw.

Tightening torque of the M12 screws : 130 N·m

4.3 Positioning of the dynamometer

 Dynamometers and cables must be placed in a clean

and dry environment.

 Lay the connecting cable so that it cannot get cut off

or torn out when working

Ceramic-Microvibration Dynamometer Type 9236A…

Page 12 9236A_002-883d-12.19

4.4 Basic circuitry and cabling of the measuring system

The electrical charges (in pC) delivered from the measur-

ing platform are converted by charge amplifiers into pro-

portional voltages, which may be displayed, recorded or

further processed with usual instruments.

The following rules should be observed when cabling

the measuring rig:

 The connecting cable from dynamometer to charge

amplifier must have high insulation and low frictional

electricity. Use only the specified cables therefore

 The cable should be laid directly between the dyna-

mometer and the charge amplifier without loops to

avoid additional noise. Ideally, it should lie flat on a

conductive and grounded surface.

 Ordinary cables may be used to link the charge am-

plifiers with the display or evaluation instruments

 Make sure that all work with electrical connections is

done carefully and cleanly. Remove the protective

caps from the connections only immediately before

connecting a cable

 Cabling instructions for specific configurations are

given in the two sections following

Assembly, installation and putting into operation

9236A_002-883d-12.19 Page 13

4.4.1 Force measuring with 3 components (F

x

, F

y

, F

z

)

The following figure shows the elements required for the

connection of the dynamometer to a high-quality multi-

channel charge amplifier Type 5080A, in order to achieve

the lowest possible noise level. It is a ground-insulated

measuring chain with 3-wire cable.

The assignment of the connection cables for the 3 component measurement and the corresponding

extension cable are shown in the figures below. Alternatives to the Type 1687A... cable are listed on

the Type 9236A data sheet ( Doc. No. 003-460).

Fig. 3: Allocation of connection cable Fig. 4: Allocation of extension

3 component measurement cable 3 Component

measurement

Ceramic-Microvibration Dynamometer Type 9236A…

Page 14 9236A_002-883d-12.19

4.4.2 3-component force measurement

The design of a dynamometer ensures that the forces

applied exert no moments on the individual force sensor.

The force sensor can therefore be loaded up to the max-

imum defined measuring range (moment-free). With re-

gard to the zero point of a dynamometer, however, a

force vector whose line of action does not go through this

zero point will produce a moment. Moments cause some

of these sensors to be subjected to an additional load in

one or more directions.

For a 3-component force measurement with a dynamom-

eter consisting of four 3-component sensors, the output

signals (each of Fx, Fy and Fz) of the four sensors are

summed. However, the sum of the four sensors always

shows the correct value irrespective of the force applica-

tion point.

A 3-component dynamometer measures

 the three components of all the resulting forces

acting on the dynamometer and their direction but

not their position in space

Depending on the location of the force application point,

the load is distributed over all four sensors. However, al-

ternatively, an individual sensor can receive the main part

of the force. If the force is applied far outside the dyna-

mometer then, according to the law of the lever, an indi-

vidual sensor can experience a multiple of the force to be

measured. For applications of this kind, the load on an

individual sensor must be accurately calculated.

The following rule of thumb applies to the meas-

uring range of a dynamometer

If the force application point of the resulting force

vector is within a pyramid consisting of the cover plate

surface and a height corresponding to the shorter

side of the cover plate, then the maximum measuring

range of an individual force sensor applies for the

entire plate.

If there is a possibility of the acting loads damaging the

dynamometer, please contact your Kistler Customer Ser-

vice Center, where an analysis can be carried out for

your load case.

Assembly, installation and putting into operation

9236A_002-883d-12.19 Page 15

4.4.3 Force and moment measuring with 6-components (F

x

, F

y

, F

z

, M

x

, M

y

, M

z

)

The illustration below shows the elements needed to con-

nect the dynamometer to a high-quality multichannel

charge amplifier Type 5080A..., in order to achieve the

lowest possible noise level. It is a ground isolated meas-

uring chain with 8-wire cable.

The assignment of the connection cables for the 6-component measurement and the corresponding

extension cable are shown in the pictures below. Alternatives to the Type 1677A cable are listed on

the Type 9236A data sheet (Doc. No. 003-460).

Fig. 5: Allocation of connection cable Fig. 6: Allocation of extension

Type 1677A cable Type 1678A

Ceramic-Microvibration Dynamometer Type 9236A…

Page 16 9236A_002-883d-12.19

The individual forces and torques can be calculated as

follows:

Fx = Fx1+2 + Fx3+4

Fy = Fy1+4 + Fy2+3

Fz = Fz1 + F z2 + F z3 + F z4

Mx = b  (Fz1 + F z2 – F z3 – F z4) · kMx

My = a  (–Fz1 + F z2 + F z3 – F z4)  kMy

Mz = b  (–Fx1+2 + F x3+4) + a  (F y1+4 – F y2+3)  kMz

In den obigen Formeln sind a und b die Dynamometer-

Konstanten, während kM Korrekturfaktoren darstellen.

The values for Type 9236A1 are:

a = 80 mm

b = 80 mm

The values for Typ 9236A2 are:

a = 120 mm

b = 120 mm

Deviations occur when measuring the torques because a

dynamometer is not infinitely stiff. These deviations are

corrected by the correction factors kMx, kMy and kMz.

They are normally not provided but must rather be de-

termined through a special calibration. The design of this

special calibration must be as close as possible to the

real measurement design to prevent measurement inac-

curacies.

If the correction factors are available, then they must be

included in the calculation. Depending on the characteris-

tics, the charge amplifier Types 5080A... offers the option

to set the correction factors directly. Factor 1 is already

set for the correction factors kMx, kMy and kMz by default.

Depending on the analysis of the measuring results, the

distance between the cover plate surface and the sensor

center is the deciding factor. This distance is called az0.

The value for Type 9236A1 and 9236A2 are: az0 = 48.5 mm

Operation

9236A_002-883d-12.19 Page 17

5. Operation

5.1 Range selection

It is recommended to use the charge amplifier Type

5080A... for the multi-component dynamometer Type

9236A, in order to reach the lowest possible noise level.

Adjust the sensitivities according to the data in the calibra-

tion sheets for the channels Fx, Fy and Fz. The output

voltage is then set directly to the value corresponding to

the selected scale (...N/V). To adjust the sensitivity, con-

sult the operating instructions for the charge amplifier.

5.2 Measuring small force changes

The piezoelectric measuring technique allows very accu-

rate measurement of small force changes in the pres-

ence of high preload. If for example Fz fluctuations

around 10 N are superimposed upon a main cutting force Fz

of some 20 kN, the following rules can be applied:

Ceramic-Microvibration Dynamometer Type 9236A…

Page 18 9236A_002-883d-12.19

a Set the amplifier to <Reset>. Select the range for F as

follows: 2 · 103 N/V (amplifier to <Long Time Constant>)

b Switch the amplifier to <Operate>

c Apply Fz

d After reading and/or recording the force, switch the

amplifier back to <Reset> so that the charge corre-

sponding to Fz is led off

e Switch the amplifier over to a more sensitive scale

(e.g. 1 N/V for \Fz)

f Set the amplifier to <Short Time Constant>

g Switch the amplifier to <Operate>.

The variations of Fz can now be measured with great

accuracy, because the dynamic response threshold is

around 0,02 N. This means that a \Fz of 0,02 N (as a

change in Fz  20 kN) gives an output voltage of about

20 mV

The attainable resolution is thus:

0000001

1

!

h Switch the amplifier to <Reset>

i Switch the amplifier back to a less sensitive scale

(2 · 103 N/V). Select <Long Time Constant> and

switch the amplifier to <Operate>

k The disappearance of Fz (tool withdrawn) can also be

detected

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