HBM KMR User manual

English Deutsch
Force washer
KMR
Mounting instructions
A2114-1.1_en/de

KMR
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English
1 Safety instructions 3........................................
2 Scope of supply 6..........................................
3 Field of application and notes on use 6......................
4 Structure and function 6....................................
4.1 Measuring element 6.........................................
4.2 Measurement, output signal 7.................................
4.3 Disturbance variables 7.......................................
5 Conditions on site 7........................................
5.1 Ambient temperature 7.......................................
5.2 Protection against humidity 8..................................
5.3 External pressure 8..........................................
6 Mechanical installation 9....................................
6.1 Important precautions during mounting 9........................
6.2 General guide lines for installation 9............................
6.3 Examples for mounting 10.....................................
7 Connection 14...............................................
7.1 Allocation of the cable cores 14.................................
7.2 Connection technique 15.......................................
8 Specifications 16............................................
9 Dimensions 18..............................................

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1 Safety instructions
Use in accordance with the regulations
The KMR are intended for the measurement of forces in
test rigs / press‐fit facilities / test systems / presses. Any
other use is deemed to be not in accordance with the
regulations.
In the interests of safety the transducer should be used
only as specified in the mounting instructions. It is also
essential to comply with the statutory and safety
regulations in force for the particular application. The
same applies to the use of accessories.
The transducer is not a safety device as defined for use
in accordance with the regulations. Perfectly safe
operation of this transducer demands appropriate
transport, as well as technically correct storage,
installation and mounting combined with careful operation
and maintenance.
General dangers due to non-observance of the
safety instructions
KMR comply with the state of the art and are fail‐safe.
The transducers can give rise to residual dangers if they
are inappropriately installed and operated by untrained
personnel.
Any person responsible for the installation,
commissioning, maintenance or repair of a force
transducer must have read and understood the mounting
instructions and in particular the technical safety
instructions.

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Residual dangers
The scope of performance and supply covers only part of
measurement technology. In addition, equipment
planners, installers and operators should plan, implement
and be responsible for the technical safety aspects of
force measurement technology in such a way as to
minimise the residual dangers. Prevailing regulations
must be complied with at all times. The residual dangers
connected with the force measurement technology must
be referred to explicitly.
Warning signs and danger symbols
Important instructions for your safety are specifically
identified. It is essential to follow these instructions in or
der to prevent accidents and damage to property.
Residual dangers are highlighted in these mounting
instructions with the following symbols:
Warning sign, signal word Meaning
CAUTION This marking warns of a potentially dangerous situ
ation in which failure to comply with safety require
ments can result in slight or moderate physical injury.
CE mark
The CE mark enables the manufacturer to guarantee that
the product complies with the requirements of the
relevant EC directives (the declaration of conformity is
available at http://www.hbm.com/HBMdoc).
Statutory marking requirements for waste disposal
National and local regulations regarding the protection of
the environment and recycling of raw materials require
old equipment to be separated from regular domestic
waste for disposal.

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For more detailed information on disposal, please contact
the local authorities or the dealer from whom you
purchased the product.
Conversions and modifications
The KMR must not be modified from the design or
safety‐engineering point of view without our express
agreement. Any modification precludes liability on our
part for any damage resulting therefrom.
Qualified personnel
This instrument is to be used by qualified personnel only,
in strict accordance with the safety rules and regulations.
It is also essential to comply with the statutory and safety
regulations in force for the particular application. The
same applies to the use of accessories.
"Qualified personnel" means persons familiar with the
installation, assembly, commissioning and operation of
the product who possess the qualifications required for
their function.
Conditions on site
Protect the transducers from moisture and atmospheric
influences such as rain, snow, etc.
Maintenance
The KMR is maintenance‐free.
Accident prevention
Even though the specified nominal force in the
destructive range is a multiple of the full scale value, the
relevant accident prevention regulations of the trade
safety association must be observed.

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2 Scope of supply
SKMR
S2 hardened washers as force introduction parts
SMounting instructions
3 Field of application and notes on use
The KMR are designed to measure static and dynamic
compressive forces, and are especially suitable for the
monitoring of forces, e.g. with production processes or
bolted connections. Furthermore, they are used in the
food industry, for example.
The IP67 degree of protection also permits outdoor
measurements to be taken.
4 Structure and function
4.1 Measuring element
The KMR have been designed as welded construction
and are completely made from corrosion‐resistant,
hardened steel. They can be mounted in any position.
In the measuring element, strain gauges are connected
to form a Wheatstone bridge. The balancing elements
are located in the cable end.
Therefore, do in no case shorten the cable.

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The connection‐cable sheathing is made from
polyurethan (PUR).
4.2 Measurement, output signal
With axial forces, the measuring element is upset and the
Wheatstone bridge detuned. With a bridge excitation
voltage fed, the circuit supplies an output signal that is
proportional to the change in resistance and thus
proportional to the force applied.
Measurement signal conditioning requires an electronic
system (e.g. an amplifier) that is part of the complete
measuring chain.
4.3 Disturbance variables
Torsion, bending and side forces are disturbances that
may reduce accuracy or even damage the KMR.
5 Conditions on site
5.1 Ambient temperature
To obtain optimum measuring results, the nominal
temperature range of -10...+70 oC (+14...+158 °F) has to
be observed. Constant or, at the most, slowly changing
temperatures are most suitable. The specified
temperature coefficients apply to an ambient temperature
changing no faster than 5 K/h.

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5.2 Protection against humidity
Ambient humidity and tropical climates do not impair the
function of the KMR. The KMR complies with IP67
degree of protection according to DIN EN 60529.
IP67 means: Protection against the penetration of dust,
and protection against water, if the KMR is dived into
water (test condition: 0.5 h in 1 m water depth). To
prevent penetration of condensation water, bend the
cable to form a drip loop.
right wrong
Fig. 5.1 Drip loop
5.3 External pressure
The permissible external pressure is 0...3 bar.

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6 Mechanical installation
6.1 Important precautions during
mounting
SHandle the KMR with care.
SThe KMR must lean plainly on the clean supporting
surface and may not bend.
SAlways use the supplied washers for force
introduction (do in no case bring spring washers, tooth
lock washers etc. into direct contact with the KMR).
6.2 General guide lines for installation
To determine the absolute value of the force to be
monitored, you have to calibrate the KMR with a test
transducer while it is in its final mounting position.
Depending on the mounting position, there are significant
changes in output signal. The following factors are
effective:
SFriction
SStiffness of the components
SSurface unevenness
SAsymmetric force introduction
After calibration, the mounting position may not be
changed.

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6.3 Examples for mounting
The following examples for installation show the various
possibilities to use the KMR.
SMonitoring flange joints
With this measurement set‐up, critical flange joints or the
setting of screws (max. property class 14.9) can be
monitored.
CAUTION
Please ensure when tightening the screws that the
connecting cable is not sheared off. Slightly lubricate the
supporting surface of screw head or nut to prevent the
transducer from turning during fastening of the screw.
You thus avoid shearing off the cable connection.
KMR
Washer
Washer
Fig. 6.1 Monitoring a screw preload

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SMonitoring working loads with bolted connections
When using the KMR in a bolted connection to monitor
working loads (e.g. pressure increase in a value, press
forces), you have to take into account the stress diagram
for bolted connections.
The KMR measures the change in the screw preload. If
you want to deduce the working load from the force
Fmeas, then the actual stiffness of the screw and of the
screwed parts must be considered.
Fmeas
FP
Change in length
Fmeas
FW
Fmeas = changed preload due to the working load
FP= Screw preload
FW= Working load Force
Fig. 6.2 Stress diagram

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SMonitoring press forces with pressure plates
The following measurement set‐up also enables you to
determine press forces. The hardened washers may be
omitted, if the hardness of the pressure plates is at least
43 HRC.
Stamp
Retainer
Blank
Die‐plate
KMR
Ejector
Fig. 6.3 Monitoring a pressing force
SMonitoring rope forces with tension rods
The KMR has been designed for compressive forces.
Due to its internal bore hole it may also be used to
monitor tensile forces. Take into account the tensile
strength of the tension element in use.

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Washers KMR
Shackle
Thimble
Fig. 6.4 Monitoring rope forces

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7 Connection
7.1 Allocation of the cable cores
The KMR connection cable has colour‐coded free ends.
It is 1.5 m long. With amplifiers with connection sockets,
you first have to solder a plug onto the cable. The cable
screen (ye) is not connected to the transducer ground. It
has to be connected to the amplifier's operating voltage
zero (contact 12, E, 1).
If the transducer is connected according to the
indications given in the table, the output voltage at the
amplifier is positive when the transducer is charged in the
indicated direction of force. If with compressive
transducer forces a negative output voltage at the
amplifier is required, simply interchange the white and
red cable cores.
The pin assignment for some of the HBM amplifiers can
be taken from the following table or you can refer to the
respective operating manual for your amplifier.
Connection
Connection to an amplifier with
Core
color
Terminal or
soldered
connection
7-pole
connection
plug
15-pole
D-plug
Measurement signal (+) White 22 A 8
Bridge excitation voltage (‐) Black 21 B 5
Bridge excitation voltage (+) Blue 20 C 6
Measurement signal (‐) Red 19 D 15
Shield to earth Yellow 12 E 1

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7.2 Connection technique
The KMR are equipped with a four‐core connection cable
and calibrated in four‐wire technique as standard.
Bridge excitation voltage
Measurement signal
Cable shield
Fig. 7.1 Transducer with four-core connection cable

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8 Specifications
Type KMR
Nominal force kN 20 40 60 100 200 300 400
Sensitivity range mV/V 1.7...2.31)
Temperature effect on the
sensitivity per 10 K
in the nominal temperature
range
% 1
Temperature effect on the
zero signal per 10 K
in the nominal temperature
range
% 0.5
Linearity deviation
Hysteresis,
related to the full scale value
%
%
10
10
Repeatability
with identical mounting position
with different mounting position
%
%
1
10
Creep over 30 min.,
at ambient temperature % 2
Input resistance at ambient
temperature Ωu345
Output resistance at ambient
temperature Ω 300...400
Insulation resistance GΩ u5
Reference excitation voltage V 5
Operating range of the
excitation voltage V 0.5...5 0.5...12
Nominal temperature range °C[°F] ‐10...+70 [+14... +158]
Operating temperature range °C[°F] ‐10...+70 [+14... +158]
Storage temperature range °C[°F] ‐30...+85 [-22... +185]

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Limit force % 150
Breaking force %u500
Relative static lateral-force
limit % 20
Nominal displacement "15 %
Natural frequency "15 %
mm
kHz
0.06
22
0.06
45
0.06
47
0.08
27
0.11
22
0.21
18
0.32
15
Weight, without cable g 5 7 12 32 40 50 70
Permissible dynamic force
(oscillation amplitude to DIN
30100)
% 50
Protection to DIN EN 60529 IP 67
1Depending on the scaled mounting position, the KMR sensitivity ranges between 1.7...2.3 mV/V.

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9 Dimensions
Dimensional variation to DIN7168-coarse
KMR: 100 kN, 200 kN, 300 kN und 400 kN
(mit PG gland and ball radius R)
KMR: 20 kN, 40 kN, 60 kN
Hardened
washer
Cable Ø 2.8; 1.5 m
long, pigtails
Bending radius:
min. 29 mm Bending radius:
min. 29 mm
B
B
Y
Z
A
X
X
A
F
D
G
G
EC
SW
D
R
A
B
KMR, measurement
Nominal
(rated)
force in kN
jA-0.1 jB+0.1 jC D jE G R jX
appr.
Y
appr.
Z
appr.
20 17 6.5 - 6 9 0.5 - 6 11.5 25
40 21 8 - 6 13 0.5 - 6 11.5 25
60 24 10 - 8 16 0.5 - 6 11.5 25
100 26.5 12.7 19.75 10 - - 6 10.5 14.5 -
200 31 16 25.5 10 - - 8 10.5 14.5 -
300 37 21 31.5 10.5 - - 9 10.5 14.5 -
400 46 25 38 12.5 - - 10 10.5 14.5 -

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Hardened washer, measurement
Nominal (rated) force
in kN
jA-0.1 jB+0.1 Ffor screw AF
20 17 6.5 3 M6; 1/4“ -
40 21 8 3 M8; 5/16" -
60 24 10 4 M10; 3/8" -
100 26.5 12.7 5 M12; 1/2“ 9
200 31 16 6 M16; 5/8" 9
300 37 21 6 M20; 3/4" 9
400 46 25 8 M24; 7/8" 9

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