Note: Descriptions are shown in the official language in which they were submitted.
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Device for measuring the thickness profile of rolled sheet
metal bands
The invention relates to a device for measuring the
thickness profiles of rolled sheet metal pieces or sheet metal
bands with an X-ray tube, with a movable diaphragm being
closely arranged therehefore, radiation receiver being spacedly
arranged and firmly installed along a line and directed toward
the radiation, with the sheet metal piece or sheet metal band
to be measured being passed through the radiation between the
X-ray tube or the sli-t diaphragm and the radiation receivers
in such a way that its width extends along the line of the
firmly installed radiation receivers, and a processing device
is connected to the radiation receivers and a transfer means
of the slit position, said processing device being intended for
determining the radiation absorption and the allocation of the
thickness of the sheet metal band and the measuring ranges
distributed over the width of the sheet metal bands, said
processing device further being connected with a display
device.
A device for measuring thickness profiles is known
from German Patent Application OS 31 40 714 published April 28,
1983 in the names of ~lormann et al. It has the drawback that
only relatively inaccurate measurements can be made. Due to
the size of the receiver, it is not possible to subdivide the
sheet metal band to be measured into narrow sections between
which there are no unmeasured portions. A further shortcoming
MLS/lcm
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2~g
is that the number of the radiation receivers used is very
large. This makes the apparatus complicated and expensive.
U.S. Patent 3 866 047 discloses another device which
obviates these drawbacks because it uses wide radiation
receivers and a movable slit diaphragm.
The disadvantage of this apparatus resides in the fact
that only a few measuring values can be obtained per second
because the slit diaphragm can only be moved very slowly in an
oscillating fashion since it must have a great mass for the
purpose of screening when used for measuring sheet metal bands.
The reason is that in this case a high radiation energy is
re~uired. This great mass also causes a swinging movement of
the entire stand, whereby, especially in the case of having
great distances between the source of radiation and the
radiation receiver, small measuring areas are not possible.
The small number of measurements per second renders
this apparatus unsuitable for supervising a fast-moving rolling
mill. ~or use in a rolling mill, particularly in a wideband
rolling mill, it is further necessary that a very large space
is kept between the X-ray tube and the radiation receiver
through which the sheet metal band to be measured is guided.
On a roll table the edge parts of the metal sheets often jump
up and would destroy the measuring device if there were not a
free space of more than 2000 mm above the roll table.
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It is an object of the invention to provide a
measuring apparatus Eor use in a rolling mill oe on roll tables
which yields a very large number of measuring values per
second, wherein for the purpose of a very great local
resolution the sheet metal band is subdivided into very small
stripes which are distributed over the width of the band,
between which there are practically no gaps and wherein the
distance between the slit diaphragm and the radiation receivers
is very great for reasons of safety and an extremely good
measuring accuracy is attained.
This object is achieved by having the slit diaphragm
rotatably journaled in a circular arrangement around the part
of the X-ray tube which emits the ~-rays and driven by a drive
means.
An embodiment is described with the aid of Figs. l to
3.
Fig. l shows the apparatus with the X-ray tube and
the slit diaphragm and the radiation receivers,
Fig. 2 qives a view of those devices which are
connected at the outside of the radiation receivers; and
Fig. 3 illustrates a slit diaphragm which is composed
of two rings.
The X-ray tube 11 is circularly surrounded by a slit
diaphragm 12. The slit diaphragm is journaled by means of the
three rollers 28, 29 t 30. One of these rollers is driven by a
motor, accurately regulated in its speed of rotation.
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The speed o~ rotation can be uniform. However, it can also
be variable and. m~y, for example, be coupled with the
v~ri3ble band speed.
The slit diaphr~m 12 need ha.ve only one slit 13 if it has
a relatively ~reat speed of rota.tion. If there is more than
one slit in the slit di3~hra~m 12, the speed of rotation can
be chosen smaller. It is favor~lble to have so many slits 13
that a radiation receiver is hit by a new ray at one of its
ed~es shortly after the previous ray, passin~ at the opposite
ed~e, has left it. In Fi~. 1 ten radiation receivers 14 to
23 are arranged below the sheet metal band to be measured.
They need a cone of ray~ which includes, for example, an
an~le of about 36~. On the correspondin~ seEment of the
slit diaphragm 12, which also includes an angle of about
36~ , a~ most only ten slits may be providel.
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At the be~inning of the line of radiation receivers an
auxiliary detector 25 is arranged. The arr~r 26 at the : ;.
slit diaphra~m indicates tne direction of rotation of the
1it dia.phra~mO
The auxiliary detector 25 is first lmp1nEed by the ray
from the slit 13. The detector causes a ~iEnal which
starts the chopper 42. Thi~ cho per 42 su~divide~ into
time intervals all measuring si~na1~ co~inE from t~e
radiation receivers 14 to 23, which si~na.l~ la.st as long
as a ra~ need~ to pas~ the width of a-mea~rin~ ran~e on
the ~heet metal band 24. The width of the radiation
receiver corresponds to several measurinE ranges.
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The radiAtion receiver 14 shown in Fi~. 2 conta.ins five
me3surin~ r3n~es which 3ra repre3ented by dashed lines
and referenced 31 to 35. Of the radiation receiver 15
po~itioned a.~Jacent thereto~the measuring ran~es 36 to 39
are indicated. In Fi~. 2 the ray 40 whlch has Just passed
the slit dia.phra.Em 12, is in the measurin~ ran~e 32,
whereas the next followlnE slit in the slit diaphraEm 12
allow3 to pas3 a ray 41 onto the measurin~ r~n~e 37 of
the followin~ radiation receiver 15. In Fi~. 1 only a. very
few slits are illustr3ted. Many more sl~its would have
to be pre3ent if~such a dense sequence~o~ rays i5 to be
attained as is indicated in Fi~. 2 by the rays 40 and 41.
If the slit dla~hra~m 12 ls rotated ln the dlrection of
the arrOw 26, the ray 40 passes the measurin~ran~es from
the radl~tion receiver 14 ln the dlreotlon of~the radia.tion~
recelver 15. The ray 40 first impln~es~on t~he auxili~a.ry ~ ~ -
detector 25, a.s a result of whlch it ~ives a:current impulse
to the~chop~er. This lmpulse starts~ the~ chop~er 42. When~
the ray 40 PaSseS over the mea.surin~ ranEe 31, the ray is ; ~ :
waakened i.n accordance wlth the thlckness of the sheet
metal band 24 to be penetr;t~ed. In~the radlatlon receiver
14 a current is~:created which depenas~on the intensity of ; ~ ;
the ray~ 40. This current flows via:the amplifier 43~and
vi; the chopper:~42 to the tran;fer means 44 lnto the ; ~
processin~ de~ice 45 where it; i9 transformed~lnto a ~ ~ ;
mea;urlnE v3.lue oorrespondlnE to:the thickne;s of t~he~sheet
metal band 24.~ Thls me;;urinE va~lùe~is pa~;sed on~to the ~ :
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di3play unit 46. In addition to a display unit rurther
devices, e.~. for correctinE the rollin~ operation, c3n
be connectedO
The chopper 42 interrupts the current comin~ from all
radiation receivers for a short time. Thq frequency of
these interruptions aErees in its timin~ exactly to the
number of slits 13 and to the speed of rota~tion o~ the slit
dia~hraEm 12.
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In the transfer means 44 the number o~ current inter-
ruptions of the chopper is also counted, i.e. as of the
start cau3ed by the auxiliary detector~25.~ The ti~e
between two interruptions of the chopper 42~corresponds to
the time needed by the~ray 40~for~passln~over~the measu-
rin~ ran~e 31, for example. The amplifler~43 imposes
upon the output ourrent an ldentifloat~lon~siEnal w'nich
differs from tne~i~dentification~ nal9~0~ the other
amplifiers~which are connected at the outlet~side o~ the~
other radiation recelversO~The transfer means 44 rec~o~
nlzes from~the identification signal:, to whlch radiation~
recelver~the mea~surln~value belon~s; and the number~of~
interruptlon~ also~counted~by the~chopper 42,~tell~ the~
tr3nsfer~`means ln~which measurin~ ranE~e~of the respectlve~
redlatlon recelver the ray ls;at thls~tlme.~
The transfer means;44 gives~the measurlng value, together
with the~si~nal belon~lng to~each measurlnE ran~e, to the ~;
procesRinE~d-v~ce 45.~ hls l~substantlally e~pro~remed
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com~uter which, ln a wa~ known per se, calculates tne
thic'.mess o~ the sheet metal band 24 from the measured
intensi.ty o the received ray, in which calculation any
disturbin~ influences are corrected. It is, for example,
tal~en into consideration and corrected tha.t the distrl-
bution of intensity of the X-ray tube 11 over the width o~
the radiation window is not uniform. Also, the different
len~ths of the path of the ray and the different an~le3
of incidence in the radiatlon recelver between ra.diation
receivers which lie, for example, in the middle of the .~ :~
sheet metal band 24 and the edEe, or the different reception
over the width of the radiation receiver, are corrected. :
The values of the various measurlng ra.n~es can be pa.ssed
on to a dlsplay device 46, the display~panel of whlch is
subdivlded into the same number of mea.surin~ ranEes.
A small strlpe on the display panel of~t:he~display devlce
46 corre~pond3 analoEously and with respect to lts positi~on
to each measurln~ ran~e~31 to 39~ The~se~stripes a.re indi~
cated by d~shed lines. The values of thloknes3 of the~
sheet metal:band 24 can~be displayed diE~i:tally. However, ~ :
it is also~possible to show them by~dots~:on the display
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panel with the hei~ht of~each dot c~orresponding to the
respect~ive thickness. The~dots can~also be interconnected ;
to form a~curve. And it is~`possible to attach any other
kind of display deviceO ~ ~ ~
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The chopper is switched off by the counter in the transfer
means 44 when it has rea.ched the number 5 in Fi~. 2.
A short pa.use follows:untll a new ra.y implnEes onto the
auxiliary~detector 25.
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The synchronlza.tion between the slit diaphra~m 12 and the
cho~per 42 becomes also possible by the fact that at the .:.
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slit diaphr3~m 12 a reliable operatin~ counter of the
number of revolutions la provlded w~ich is connected to
frequency ~enerator in the chopper. The chopper can
have the ~orm of a tri~Eer-impulse EeneratorO
3uitable for use as radlation recelvers are, for example,
plastic scincillators which are connected at the outlet
side in a known manner to photo~ultipliers and ampllflers
or countin~ devices.
The slit diaphra~m can, a9 indlcated:ln~Fi~.. 3, also
consist of two concentric rin~s:which are, for example,
connected by ~pokes:47 and 48. It is:àlso~possible to
use more than two:rinFs~
Due~to the:oonslderable measuring:resolut~ion the positl~on
of the~sheet metal ed~es and~thUs the~wldth~ of the sheet:;~
metal~band~can be ea.sil,y; determlned.
The invention is:not restricted to the~described emb~odiment~
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