Kistler 9253B21 Owner's manual

Instruction

Manual

Multicomponent

Force Plate

Type 9253B…

9253B_002-050e-12.14

Instruction

Manual

Multicomponent Force

Plate

Type 9253B…

9253B_002-050e-12.14

Foreword

Page 1 9253B_002-050e-12.14

Foreword

We thank you for choosing a Kistler quality product

distinguished 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

obligation to notify any person or organization of such

changes or improvements.

expressly provided herein, no part of this manual may be

reproduced for any purpose without the express prior

written consent of Kistler Group.

Kistler Group

Eulachstrasse 22

8408 Winterthur

Switzerland

Tel. +41 52 224 11 11

Fax +41 52 224 14 14

[email protected]

www.kistler.com

Multicomponent Force Plate, Type 9253B…

Page 2 9253B_002-050e-12.14

Content

1. Introduction ................................................................................................................................... 4

2. Important Information .................................................................................................................... 5

2.1 For Your Safety .................................................................................................................... 5

2.2 How to Treat the Instrument ................................................................................................ 6

2.3 Tips for Using the Instruction Manual .................................................................................. 7

2.4 What Happens After Modifications? .................................................................................... 7

3. General Description of the Instrument ........................................................................................... 8

3.1 What does a Multicomponent Force Plate do? ..................................................................... 8

3.2 Functional Principle .............................................................................................................. 9

3.3 Design of the Multicomponent Force Plate ........................................................................ 10

4. Assembly, Installation and Putting Into Operation ...................................................................... 11

4.1 Important Remarks ............................................................................................................. 11

4.2 Installing the Force Plate .................................................................................................... 11

4.3 Dynamometer Positioning .................................................................................................. 12

4.4 Basic Circuitry and Cabling of the Measuring System ......................................................... 13

4.4.1 Force Measuring with 3 Components (Fx, Fy, Fz) .................................................... 14

4.4.2 3-Component Force Measurement ........................................................................ 15

4.4.3 Force and Moment Measurement with 6 Components (Fx, Fy, Fz, Mx, My, Mz) ....... 16

5. Operation ..................................................................................................................................... 18

5.1 Range Selection .................................................................................................................. 18

5.2 Measuring Small Force Changes ......................................................................................... 18

5.3 Usable Frequency Range .................................................................................................... 20

5.4 Temperature Influences ...................................................................................................... 24

5.5 Polarity of the Measuring Signal ......................................................................................... 24

6. Maintenance ................................................................................................................................ 25

6.1 Recalibrating the Instrument .............................................................................................. 25

6.2 Maintenance Tasks ............................................................................................................. 26

7. Troubleshooting ........................................................................................................................... 27

7.1 Diagnosis and Rectification of Faults .................................................................................. 27

7.2 Defective Multicomponent Force Plate ............................................................................... 28

8. Technical Data ............................................................................................................................. 29

8.1 3-Component-Dynamometer Type 9253B… ..................................................................... 29

8.2 Accessories ......................................................................................................................... 32

Content

9253B_002-050e-12.14 Page 3

9. Annex ........................................................................................................................................... 33

9.1 Glossary .............................................................................................................................. 33

9.2 Measurement Uncertainty .................................................................................................. 37

9.3 Linearity .............................................................................................................................. 38

9.4 Frequency Range ................................................................................................................ 41

9.5 Influence of Temperature .................................................................................................... 43

Total pages 44

Multicomponent Force Plate, Type 9253B…

Page 4 9253B_002-050e-12.14

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 measuring

technology:

 Piezoelectric sensors for measuring force, torque, strain,

pressure, acceleration, shock, vibration and acoustic-

emission

 Strain gage sensor systems for measuring force and

moment

 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, manufacturing,

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

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

extensive support organization.

Important Information

9253B_002-050e-12.14 Page 5

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 force plate 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 force plate on the mounting surface according

to the instructions. See section 4 "Assembly,

Installation and Putting Into Operation" for details.

Important!

Fix all parts mounted on the top plate of the force plate

according to the forces expected!

Warning!

Danger of injuring your hands! Move the force plate

only by using the eyebolts supplied.

Multicomponent Force Plate, Type 9253B…

Page 6 9253B_002-050e-12.14

2.2 How to Treat the Instrument

The force plate may be used only under specified

environmental and operating conditions.

 The insulation resistance is crucially important with

piezoelectric measurements. It must be around 1014 Ω

(but at least 1013 Ω).

 To obtain this resistance, all plug and socket

connections 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 the force plate to the

charge amplifier) is highly insulating. Use the proper

cable only.

 Do not remove the connecting cable from the force

plate.

 When not in use keep the dynamometer in the original

packaging to protect it.

 When performing long-time measurements, make sure

that the temperature of the force plate remains as

constant as possible.

Important Information

9253B_002-050e-12.14 Page 7

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 force

plates you can confine your reading to the information that

you really need.

We have endeavored to arrange these instructions so that

you can find the information you need without difficulty.

Please keep this Instruction Manual in a safe place where it

can be consulted any time.

If the instructions get lost, just turn to your Kistler customer

service station and they will be replaced without delay.

All information and directives in this Instruction manual

may be modified at any time without notification.

2.4 What Happens After Modifications?

Modifications to instruments result in alterations of the

Instruction Manual as a rule. In such cases, enquire at your

Kistler customer service station about the possibilities of

updating your documentation.

Multicomponent Force Plate, Type 9253B…

Page 8 9253B_002-050e-12.14

3. General Description of the Instrument

3.1 What does a Multicomponent Force Plate do?

The multicomponent force plate provides dynamic and

quasi-static measurement of the 3 orthogonal components

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

plate.

With the aid of optional evaluation devices the 3 moments

Mx, My and Mz can be measured as well.

The force plate has high rigidity and hence high natural

frequency. The high resolution enables very small dynamic

changes to be measured in large forces.

The force plate measures the active force regardless of its

application point. Both the average value of the force and

the dynamic force increase may be measured. The usable

frequency range depends mainly on the resonance

frequency of the entire measuring rig (top plate,

foundation).

Fig. 1: Type 9253B…

Most important applications fort he multicomponent force

plate are:

 Cutting force measurements in milling, grinding and

other machining operations

 Ergonomic measurements

 Measurements on stamping machines and presses

 Measurements of impact forces

 Measurements of wheel forces

 Measurements of supporting forces

General Description of the Instrument

9253B_002-050e-12.14 Page 9

3.2 Functional Principle

The force to be measured is introduced via a top plate and

distributed between four 3-component force sensors

arranged in a force measuring element.

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

measurement is virtually without displacement.

In these four force sensors the force introduced is broken

down into three components.

Fig. 2: 3-Component force sensor

For the force measurement in 3 components the individual

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

negative charges occur at the connections. Negative

charges give positive voltages at the output of the charge

amplifier, and vice versa.

Multicomponent Force Plate, Type 9253B…

Page 10 9253B_002-050e-12.14

3.3 Design of the Multicomponent Force Plate

The multicomponent force plate consists of four force

measuring elements each comprising one 3-component

force sensor under preload.

The integrated 3-wire cable runs in a protective tube. The

four cables are connected together in a summing box.

The four force sensors are mounted ground-insulated.

Ground loop problems are largely eliminated in

consequence.

The multicomponent force plate is rustproof and protected

against ingress of splash water and coolant.

Together with the connecting cable Type 1687B5 or

1677A5 the multicomponent force plate meets the

requirements of degree protection IP67.

1 Force measuring element

2 Integrated cable

3 Summing box

4 Connector

5 Top plate customer side

6 Lateral cover

Assembly, Installation and Putting Into Operation

9253B_002-050e-12.14 Page 11

4. Assembly, Installation and Putting Into Operation

4.1 Important Remarks

The multicomponent force plate is a precision instrument,

but its inherent accuracy can be exploited and retained

only if it is treated with care. The following rules should

therefore be noted:

 Never drop the force plate 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 force plate on the machine table and about

the base circuitry and cabling of the measuring equipment.

4.2 Installing the Force Plate

To install the force plate correctly please observe the

following points:

 The force plate must be installed only by persons

familiar with the device and sufficiently qualified for this

work.

 Connect the connecting cable first to the force plate.

Both connecting sides (plate and cable) must be cleaned

with cleaning and insulation spray Type 1003. The O-

ring is fitted to seal the connection. The contact

surfaces for the O-ring must be clean. Insert the O-ring

and bolt the flange of the cable to the summing box

with the two bolts and tighten until it fits.

 Before installing the force plate on a machine tool or a

test rig check the flatness of the installation surface.

Uneven contact surfaces cause internal distortions

which expose the individual force sensor to additional

strong axial load an can increase crosstalk.

 The bearing surfaces of the load sensing device (bases)

are finely machined. The device must therefore be

installed only on surfaces which are ground or finished

to comparable standard. Clean the bearing surfaces

thoroughly before assembling.

 The force plate is aligned on the machine table with the

help of one of the longitudinal sides of the plate.

 Make sure that the force plate rests absolutely flat.

Even the smallest air gap will cause undesirable

Multicomponent Force Plate, Type 9253B…

Page 12 9253B_002-050e-12.14

elasticity and reduce the resonant frequency of the

measuring rig. All mountings must therefore be

considered from the vibration aspect also.

 Check whether the force plate rocks by alternately

pressing on diagonally opposite corners of the force

plate. Any rocking is clearly audible.

 If there is rocking, lift the force plate off and insert one

of the shims supplied together with the force plate. If

the thinnest shim is too thick, a piece of aluminium foil

may prove suitable. Insert shims at one corner only.

 Whenever possible, the connecting cable should be left

connected permanently to the force plate.

 Slightly grease the four supplied hexagon socket head

cap screws M12x30 and slide them into the four bores

of the force plate.

 Before tightening the screws check wether there is in

fact no rocking over the diagonals.

Important:

Before tightening the fastening screws consideration

should be given that there are no extreme temperature

differences between the force plate and mounting

surface. Otherwise there is the danger of high internal

stresses between force plate and mounting surface when

the temperatures adjust.

 Tighten the four hexagon socket head cap screws M12

with a tightening torque of 90 N·m. (A hexagon

extension bar is supplied together with the force plate.)

 Under slight pressure with the palm and simultaneous

twisting insert the four tops into the top plate.

4.3 Dynamometer Positioning

 The dynamometer and the cables must be posi-tioned

so that coolants can drain completely. This stops

aggressive bacteria forming in old coolant, which could

then damage the dynamometer and the cables.

Depressions and creases should therefore be avoided

 Install the connecting cable so that it can neither shear

off nor be pulled out when working

Assembly, Installation and Putting Into Operation

9253B_002-050e-12.14 Page 13

4.4 Basic Circuitry and Cabling of the Measuring System

The electrical charges (pC) supplied by the force plate are

converted by charge amplifiers into proportional voltages

which can be displayed, recorded and processed with the

usual instruments.

Please note the followin

g

as re

g

ards connectin

g

the

measuring system:

 The connecting cables from the force plate to the

charge amplifier must have a high level of insulation

and a low level of frictional electricity. Only the

recommended connecting cables should therefore

be used.

 Ordinary cables can be used for the connection

between the charge amplifiers and the display and

evaluation instruments.

 All electrical connections must be made cleanly and

with care. The connection cover caps should not be

removed until immediately before connecting the

cable.

 Please follow the instructions for cabling specific

configurations in the two following sections.

Multicomponent Force Plate, Type 9253B…

Page 14 9253B_002-050e-12.14

4.4.1 Force Measuring with 3 Components (Fx, Fy, Fz)

The illustration below shows the elements needed to

connect the force plate with a 3-channel charge amplifier

(such as Tyep 5070Ax01xx). It is a ground-insulated

measuring chain with 3-wire cable.

Fig. 3: Force measurement with 3 components (Fx, Fy, Fz)

The connecting cable Type 1687B5 and the extension

cable Type 1688B5 are wired as follows:

Input Output Input Output

Pin No. Out

p

ut si

g

nal

1 Ground (GND)

2X

3

–

4Y

5

–

6Z

7

–

8

–

9

–

Fig. 4: Allocation connecting cable Fig. 5: Allocation

Type 1687B5/1689B8 extension cable

Type 1688B5

Assembly, Installation and Putting Into Operation

9253B_002-050e-12.14 Page 15

4.4.2 3-Component Force Measurement

The form of dynamometer construction ensures the acting

forces do not exert any moments on the individual force

link. The force link can therefore be loaded (without any

moments) up to the maximum defined measuring range.

However, a force whose line of action does not pass

through the zero of the dynamometer produces a moment

relative to this zero. These moments cause the sensors to

be subjected to an additional load in one or more

directions.

For 3-component force measurement with a dynamometer

consisting of four 3-component force links, the output

signals (Fx, Fy and Fz in each case) of these links are

summed. However, irrespective of the force application

point, the sum of the four force links always indicates the

correct value.

A 3-component dynamometer measures the magnitude

and direction of the three components of the forces acting

on a dynamometer, but not their spatial location.

Depending on the position of the force application point,

the load is either distributed between all four force links or

an individual force link can take most of it. If the force acts

well outside the force plate, lever action can cause an

individual force link to be subjected to a multiple of the

force to be measured. For such applications the load on an

individual force link must be accurately calculated.

For information about the maximum space of the force

application point please see chapter 8.1.

If there is a possibility of the acting loads damaging the

dynamometer, please contact your Kistler Customer Service

Center, where an analysis can be carried out for your load

case.

Multicomponent Force Plate, Type 9253B…

Page 16 9253B_002-050e-12.14

4.4.3 Force and Moment Measurement with 6 Components (Fx, Fy, Fz, Mx, My, Mz)

The illustration below shows the elements needed to

connect the force plate with an 8-channel charge amplifier

(such as Type 5070Ax11xx). It is a ground-insulated

measuring chain with 8-wire cable.

Fig. 6: Force and moment measurement with 6 com-

ponents (Fx, Fy, Fz, Mx, My, Mz)

The connecting cable Type 1677A5 and the extension

cable Type 1678A5 are wired as follows:

Input Output

Pin No. Out

p

ut si

g

nal

1 Ground (GND)

2X1 + 2

3X3 + 4

4Y1 + 4

5Y2 + 3

6Z1

7Z2

8Z3

9Z4

Fig. 7: Allocation connecting cable Type 1677A5/1679A5

and extension cable Type 1678A5

Assembly, Installation and Putting Into Operation

9253B_002-050e-12.14 Page 17

The individual forces and torques can be calculated as

follows:

Fx = Fx1+2 + Fx3+4

Fy = Fy1+4 + Fy2+3

Fz = Fz1 + Fz2 + Fz3 + Fz4

Mx = b · (Fz1 + Fz2 – Fz3 – Fz4) · kMx

My = a · (–Fz1 + Fz2 + Fz3 – Fz4) · kMy

Mz = b · (–Fx1+2 + Fx3+4) + a · (Fy1+4 – Fy2+3) · kMz

a and b are the dynamometer constants in the above

formulas, while kM represent the correction factors.

The values for Type 9253B… are:

a = 120 mm, b = 200 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

determined through a special calibration. The design of this

special calibration must be as close as possible to the real

measurement design to prevent measurement inaccuracies.

If the correction factors are available, then they must be

included in the calculation. Depending on the

characteristics, the charge amplifiers Type 5070A and

5080A offer 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 9253B… is: az0 = 54,5 mm

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