Note: Descriptions are shown in the official language in which they were submitted.
~9~
DESCRIPTION
CONTROLLED GRINDING OF ROLLE~S
FOR ELIMINATION OF CRACRS
BACXGROUND OF THE INVENTION
1. Field of the Invention
The pre~ent invention relates to a method and
apparatus for the controlled grinding o rollers for the
removal of cracks, where the roller is rotated in a
rotating mechanism, while a rotating grincling wheel having
an axis parallel to the axis o~ -the roller is pressed
against the the roller and is continuously or stepwise
dlqplaced linearly in the direction o~ the axis and
where the cracks and the ef~ect of the grinding are
tested with an ecldy current method.
2. Brief Descripti.on o the Background of the
Invent:Lon Including Prior Art
Grinding devices and te.st appara~us employinc;
- 1 -
~~
9~
eddy currents are known. The conventional methods
employing these me-thods are associated with the
disadvantage that they provide for ei-ther only
gr~Ld~L~ or only measuriny. For measuring the grinding
process always had to be in-terrupted and the eddy curren-t
test probe had to be positioned over the roller to
be investigated. This method required considexable amounts
ot time. Frequently more than necessary material was
ground off, since the number of measuring steps
were reduced to a number as low as possible because
of the time expenditure involved in the measurement.
SUMMARY OF THE INVENTIOM
1. Purposes of the Invention
It is a~n object of the present invention to
provide a method which allows to obtain test results
during the ongoir,g yrinding process~
It is a further object of the present invention
to provide a method which continuously allows to look
at a total view over the state of the complete rollex and
over the advancirlg grinding process after each grinding
passage.
It is another objec-t oE the present invention
to provide an apparatus suita~le for cooperative grinding
and testi~lg of rollers with possible defects in their
surface.
These and other objects and advantages of -the
present invention will become evident from the
description which follows.
2~ Brief Description of the Inventlon
The present invention provides a method for
controlled grindiny of roller surfaces which comprises
rotating the roller with a rotary drive, rotating a grinding
wheel having a rotation axis disposed about parallel
to the rotation axis of the roller, pressing the rotating
grinding wheel against the rotating roller at a certain
position along the axis of the roller, moving the grinding
wheel along the direction of its axis, testing the surface
of the roller with an eddy cuxrent test probe disposed
substantially at the same posi-tion along the axis of the
roller as the grindiny wheel, however, which eddy current
test probe is staggered with respect to the grinding
wheel by a suitable angle relati~e to the center a~is
of the grinding wheel and performing the testing while
the grinding wheel is rotating and interacting wi.th the
roller, and processing the signals from the eddy current
test probe.
-- 3 --
. .
The test results can be ~isplayed as to
successive partial sectors of the roller to the operator.
The sectors can correspond to subdivision lines of the
roller surface substan-tially along lines ~lrallel to
the roller axis. Furthermore, the sectors can correspond
to subdivision lines of the roller surface disposed
substantially within planes ver~ical to the roller
axis. The sectors can be displayed successively in
the circumferential direction of the roller and next
to each other in a direction parallel to the roller
axis.
The test results can be classified into d~fect
groupings and the defect groupings can be displayed. A
drive for the grinding wheel position can be controlled
according to the defect grouping determinations. The
display values can be stored in a memory and the values
before passage of the grinding wheel along the roller
surface can be compared with values after passage of
the grinding wheel. The surface of the roller can be
tested for cracks with ~he eddy current test probe.
In one aspect of the present invention there
is provided an apparatus for controlled grinding of
roller surfaces which comprises a grinding wheel,
;6~;2
a drive for the support to move the support in a
direction substantially parallel to the direction of the
axis of the grinding wheel, a rotatabl~ roller disposed
with its axis about parallel to the axis of the grinding
wheel, an eddy current test probe disposed on an eddy
current test probe arm and adapted to test the surface
of the roller.
Two support wheels c~n be mounted on the eddy
current test probe arm and be disposed on both sides of
the eddy current test probe in a direction about parallel
to the axis of the roller for providing proper relative
positioning of the eddy current test probe with respect to
the roller suxface. The wheels on the eddy current test
probe arm can be rolls. The axis of the wheels can be
about parallel to the axis of the roller and follow
about a straight line. Alterna-tively, the axis of the
wheels can be sliqhtly inclined with respect to the
axis of the roller, where the incline is such that the
wheel is adapted to follow the motion of the support in
its contact path on the roller surface. There can be
provided a contact pressure element for pressing the
wheels disposed on the eddy current test probe arm
against the roller and providiny a sliding support in
-- 5 --
\
~ 3~3~ ~ ~
a radial direction relative to the roller. The contac-t
pre~sure element can be an air cylinder. A pulling off
means can be provided for removing the eddy currént test
probe from the roller. ~ hinye means is preferred for
removing the eddy current test probe from the roller
by tilting. A rotary connection can be disposed between
the measurement arm and the eddy current tes-t probe arm
for turning the eddy current test probe away from khe
roller.
A processor can be employed for processing the
data coming from the eddy current test probe~ An eddy
current test instrument can be connected to the eddy current
test probe~ an analog digital convertex can be connected
to the eddy current t~st instrument, a digital processor
can be connected ~o the analog digital converter, a
device for subdividing the circumference of the roller
can be connected to the digital processor and a
device for subdividing the length of the roller can
be connected to the digital processor.
The device for subdividing the circumference of
thQ roller and the device for subdividiny the length
of the roller can provide a diferent electrical signal
for every ~ection of the roller above which the
6 ~
3t~
eddy current test probe is disposed.
A picture screen can be connected to the
digital processor or coordinating at least a part of
the roller surface with all sectors positively
conforming to the surface of the picture screen.
A memory can be connected to the digital
processor ~or providing the possibility o recalling to
the picture screen the data produced at the last or
next to last grinding passage or proc~ssed results
entered from the digital processor. A drive controlling
the position of the grinding wheel can allow for movin~ the
grinding wheel relative to the roller surface.
Means can be provided for elastically supporting
the wheels on the eddy current test probe arm in a
radial direction relative to the rotation axis of the
roller and preferably the means for elastically supporting
does not allow a tilting around an axis which is
orthogonal to the axis of the roller and within the
tangential contact plane of the wheels and the roller
surface in order to avoid canting of the support rollersO
A drive can be provided for controlling the
position of the grinding wheel, a processor can process
the data coming from the eddy current test probe and
a connection from the pr~cessor to the drive can allow
for disengaging the grinding wheel from the roller
surface upon meeting of a pr~set standard by the test
signals coming from the eddy curren-t test probe.
The novel fea-tures which are considered as
characteristic for the invention are set orth in
particular in the appended cl~ims. The invention i~self,
however, both as to its construction and its method oE
operation, together with additional objects and
advanta~es thereof, will be best understood from the
following description of specific embodiments when read
in connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DR~WING
In the accompanying drawing~ in which is shown
one of the various possible embodiments of the present
invention:
Fig. 1 is a schematic side elevational
view of the roller disposed in the rotary apparatus
with the measurement head at the top with test probe
arm and measurement arm and with the grinding wheel
located behind the roller;
Fig. 2 is a schematic sectional view o
~ 8 --
"
3~i6~Z
the connections from the probe and the guiding of the
grinding wheel to the processing apparatus, the display
sceen and to the printer.
DESCRIPTION OF INVENTION AND PREFERRED EMB()DI2~NTS
In accordance with the present inven-tion
there is provided an eddy current test apparatus
for the determination of cracks at the surface of
the section of the roller, which i5 opposite to the
lateral position of the grinding wheel, which test
apparatus is applied to the roller during the grinding
process and which separates the measurement data in
successive partial surfaces and displays the same to
the operator of the grinding wheel. Further, several
cracks disposed in succession in -the direction of the
circumference are determined, if the partial surfaces
are displayed as successively situated in the circum-
ferential direction of the roller. It is also possible
that the surfacec disposed neighboringly in axial
direction are displayed. A capturing of all defects
and a good total view can be achieved by displaying
the partial surfaces in circumferential direc~ion
o the roller successively and in axial direction
as neighbors.
_ g _
.,
The display becomes more clear, if the
measurement results are not given as absolutP values but
are coordinated to defect classes, which in turn ~re
displayed.
The effect of a one time grinding step can be
recognized particularly easy in the case where the values
of the display are stored and the values before the
passage of the grinding wheel are compared with values
after the performed grinding step. The process is
advantageously performed with a device, where a measuring
arm is connected to the support of the grinding wheel,
which rurls back and forth in the axial direction. The
measuring arm runs in axial direction of the roller
and the test probe of ~n eddy current test probe with
a measurement head directed toward the roller i5 a~tached
directly to the measuring arm or via an extension such
as for example a probe arm.
The measurement head of the eddy current test
apparatus is advantageously supported by the roller, if the
measuring head is disposed about in the middle between
two wheels or support rolls supported by ~he roller.
The distance of the measuring ~ead from the
roller remains the same ev~n with different diameters of
- 10 -
~ ~9~
the roller, if the rotary axes of the wheels or
support rolls are directed i.n parallel ~o the ax.is of
the roller and are disposed alon~ one line.
According to ano~her embodimen~ it is also
possible that the ro-tary axes of the wheels or support
rolls are disposed slightly at an angle with respect to
the axis of the roller, where the inclined position of
the support rolls results in a component of the direction
of motion parallel to the direc~ion of the axis and
directed in the direc~ion of the motion of the support
and where the rotation axis of the wheels is sli.ghtly
displaced from a parallel posi~ion relative to the
roller axis within a plane parallel to the contact
plane of the roller and the wheel. Such an inclined position
results in the advantage that no shifting forces from the
side attack at the support rolls, since the support
rolls in this case are tending by themselves to run
along a helical path around the roller. How~ver, upon
reversal of the direction of grinding the disadvan~age
results that in this situation also the inclined position
has to be reversed.
Differences in the diameter and unevenness
are balanced by pressing the wheels or support rolls
- 11 -
during operation by way of a contact pressure element
such as for example a spring or cylinder against the
roller and by disposing the wheels or support rolls
radially shiftable with respect to the roller. The
construction becomes particularly simple in case the
contact pressure element is an air cylinder.
In order to position a heavy roller, for
example with the aid of a crane, it becomes necessary
that the test probe head can be pulled off from the roller
or is attached by way of hinges. This is acco~plished
in ~he simplest way by providing between the measurement
arm and the test probe arm a rotary connection for flapping
the test probe away from the roller.
In order to coordinate the position of the
cracks in the roller it is advantageous that a processing
apparatus for the ~est data connected ~o the measurement
head9 which processing apparatus for example comprises
an eddy current test device and a computer, is connected
simultaneously to a device for subdividing the circum-
ference of the roller and the length of the roller
and that this device is connected such as to provide
a different electrical signal for each subdivided section
of the surface of the roller disposed closely adjacent
to the measurement head.
12 -
The eddy current test probe can be provided
by a probe comprising a coil whlch is powered ~y an
electric oscillator. The electromagnetic field sets up
losses in the roller caused by magnetic hysteresis
in the material to be tested and/or by electrical eddy
currents being set up. These losses reduce the ou~put
o the oscillator and thus give a measure of the properties
of the roller surface region. The oscillator output signals
are then processed.
Alternatively, it is possible to employ two
coils in the eddy current test probe for performing
the testing unction, where one of the coils is exciting
an electroma~netic field and where ~he second coil
picks up the response and provides a signal ~o be
processed.
The position o~ the cracks can be recognized
best by having the processing apparatus connected to
a display screen and by having a part of the surface
or the total surface of the roller position conform to
the roller surface coordinated to the face of the
display screen. For comparing the effec-tiveness of the
grinding process i~ is advantageous, if the processing
apparatus comprises a storage for all test results
- 13 -
3~
occurring at least for example at the last and/or
next to last passage of the grinding wheel at the
roller surface or for all processed results, which
is connected to the picture screen by a eall-up device.
I~ is indispensable for the supporting of the
support wheels, that they are disposed shi~table with
respect to the direction toward the roller and that
this suppor~ is fi~ed with regard ~o a rotation around
a rotation axis, which is disposed vertical to the
axis of the roller and which stands vertical to the
direction of shifting o~ thP support wh~els against
~he roller.
Thus in accordance with the present
invention an eddy current test probe apparatus 15 for
determination of the cracks in the surface of a section
o~ t~e roller ll disposed opposite to the wid~h of the
grinding wheel 14 is applied during the grinding process
and the test results are segregated for a subdivision
of the roller surface into partial sectors and thus
provided to the operator of the grinding appara~us.
The roller 11 is supported by the bearings
12 and 13 of the rotary device and is driven via shafts
in a conventional manner. The grinding wheel is posi~ioned
14 -
in front of or behi.nd the roller ll. The grinding
wheel 14 is mounted at the support 21 and can be moved
in a direction substantially toward the axis of ~he roller
11. The test probe 15 is kept at a small distance above
the top surface of the roller 11. For maintain:;ng the
distance the suppor~ wheels 16 and 17 are provided and
the rotation axis of the support wheels 16, 17 is in
turn parallel or nearly parallel to the direction
of the axis of the roller 11.
The measurement head whieh comprises the probe
15 and the support wheels 17 and 16 is supported via
vertical shifts allowing guides at the probe arm 18 and
is pressed elastically agains the roller ll via an
air cylinder not shown in the drawing. The support
provided by the vertical shifts allowing guiding elements
has to be very rigid against rotary motions, since upon
reaching of the edge of the roller 11 only one support
wheel 16, 17 is supported, however, the horizontal
direction of the rotation axis of the support wheels 16 7
17 nevertheless is to be maintained with regard to the
axis of the roller ll.
The probe 15 is positioned with its middle about
in the middle of the jacket sec~ion of the roller 11
which section is momentarily being ground do~l. The
- 15 ~
\
'3t~
probe 15 can be narrower as compared with t~e grinding
wheel 14. The probe a~m 18 is.connected to the
measurement arm 20 via the support 19, such that the
probe arm 18 can be flapped upward. A flapping upward
is necessary beore passage o the
construction blocks 29 or other hindrances. The
construction blo~ks 29 provide the support for t~e roller
during rolling operation, which frequently during grinding
procedures accompany the roller llo A passage of at least
one of these construc~i~n blocks 29 is required before
the insertion or the removal of the roller from the
supports 12 and 13. The measuremen~ arm 20 running in
a horiæontal direc:tîon or approximately at a right angle
~o the axis of the roller 11 is connected to the grinding
wheel 14 and is moved linearly along the roller 11
in correspondence with the grinding wheel 14. Based on the
guides 30 the grinding wheel 14 can b~ moved along the
longitudinal extension of the roller 11.
The posi.tion o-f the grinding wheel 14 in
~he longitudinal direction of the roller 11 is Plectrically
tested by having a potentiometer or other distance
pick-up 22 atkac~ed to the support 21, the position
of which is changed in aceordance to the distance passed
- 16 -
~ 7
over by the grinding wheel 14 along the roller 11~
which is resulting in a proporti~nal change of the
voltage uncler which the electrical current flows ~hrough
the potentiometer 22. The potentiometer 22 is
connected to a data processor 23. A second line of
a fur~her potentiometer 24 is also fed to the data
processor 23. This potentiometer 24 rotates ~ogether with
the roller 11 such that the current flowing throu~h
exhibits a voltage corresponding to the an~le of rotation.
The measured pulse provided by the probe 15
upon pass~ge of a crack is fed via ~ line to the
eddy ~urrent test Apparatus 25. This commercial instrument
provides ~ignal pulses upon ~he presence of cracks and
the amplitude o the signal pulses is related to the
depth of the crack correponding to it. The eddy current
t~st apparatus 25 is conn~cted to the interface 26.
The commercially available interface 26 transforms the
signals from the eddy current test apparatus 25, which
are provided as voltage pulses, into binary signals,
which are coordinated to various classes of defects
and which are fed to the digital processor. The digital
processor 23 connects the evaluated test results to ~he
signals from the two potentiometers 22 and 24.
17 -
sefore providing this connecti.on the signals
from the potentiometers 22 and 2~ are processed from
the voltage changes as they are generated. For this
purpose the voltage changes are coordinated to classes in
the digital processor 23. Each class corresponds to
a certain passed over distance b~ the potentiometer.
In each case a class of the potentiometer 22 disposed on
the support 21 is individuall~ connected to each class of
the potentiometer 24 and these values are stored in the
digital processor successively in each case separately.
The storage locat}ons then correspond to the sections
of the surface of the roller 11. The reference is to
sections which are successively pà~sed over upon rotation
of the roller by the probe 15. Upon a linear shiting of
the grinding wheel 14 along the roller 11 t~e next
class of the potentiometer 22 disposed on the support 2]
is individually connected to each class of the potentio-
meter 24 and these values are coordinated to the next row
of ~torage locations in the digital processor. In this
manner the values of the storage locations of the
digital processor 23 correspond to small grid surfaces
from the surface c~f the roller 11. Each evaluated test
result from the probe 15 is coordina~ed to a storage
- 18 -
"
location in the digital processor, whlch corresponds
to the grid surface passed over during the measurement.
These test results segregated according to gr:id positions
and processed are made visible on a picture screen 27
connected to the digital processor 23 and the picture
screen of the display apparatus is again corresponding
to the surface of the roller 11 su~divided into grid
surfaces, where the grid surfaces as ~o their relative
position and number correspond to ~he grid surfaces
into which the surface of the roller 11 is subdivided.
Upon occurrence of a crack in the respective grid surface
corresponding to the position of the crack a signal
occurs on the picture screen, such aq for example an
A or a cross. If no crack is present, then the
corresponding grid surface remains free. The digital
processor can be programmed such ~hat cracks of varying
depth are represented by differing signs, for example
cracks with a depth of less than 0.5 mm are represenLed
by an A and cracks with a depth of over 0.5 mm are
represented by a B.
The test results of each passage of the
grinding wheel over a surface elemen~ of the roller 11
can be stored in memory and can be recalled at any time
- 19 -
9~
from the me~ory and be displayed on the picture screen
or printed by a printer 28 ~nd be compared with the
results of the other grinding wheel passages o~er
the roller ll.
The support 21 can be moved by a drive 32
in a direction parallel to the roller axls. The drive can
be provided for example by an electric motor or by a
hydraulic element. The drive 32 can be controlled by the
digital processor 23. For example, i the processor
23 determines tha~ the cracks as observed by the eddy
current test probe are below a certain level, the
motor o the support and the drive of the grinding wheel
14 canbe interrupted automatically and the grinding wheel
can be withdrawn and the rotation of the roller can
be discontinued
It will be understood that each of the elements
described above, or two or more together, may also
find a useful application in other types of system
configurations and grinding process procedures differing
from the type described above.
While the invention has been illustrated and
described as embodied in the context of a roller grinding
system, it is not intended to be limited to the details
~ 20 -
31 ~L9~
shown, since various modifications and structural
changes may be made without departing in any way from
the spiri~ of ~he present invention.
Without further analysis; the foregoîng will so
fully reveal the gist of the present invention that others
can, by applying current knowledge, readily adapt it for
various applications wi~hout omitting fea~ures that, from
the standpoint of prior art, ~airly constitute essentlal
characteristics of the generic or specific aspects of
this invention.
- 21 -
,,^`
-
