Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Apparatus for Grinding Surfaces
- The present invention relates to an apparatus for grinding
surfaces, and especially to an apparatus which may be used for
the repair of guiding surfaces, for example cylinder surfaces
or plane surfaces, or other similar surfaces on site and
without having to demount them.
Drying cylinders in a paper machine, for example, get dirty
and wear in use, and a dirty and rough envelope surface needs
to be repaired from time to time. It may only be a question of
cleaning grinding or smoothing grinding, or of stronger
machining followed by grinding for repairing the surface. The
problem of repair on site is, on the one hand, the placing and
support of the machine tool between cylinders, and on the
other hand, the guiding of the apparatus during grinding. It
is now the general practice to drive the machine tools along
guides placed between rollers. In order to avoid the install-
ment of separate frame and control assemblies for the machin-
ing process, solutions have been developed that involve sup-
porting the machine tool on the surface to be machined and to
some other guiding surfaces available, generally on the ad-
jacent second cylinder surface.
One solution is described in the patent application W087/02281
disclosing an apparatus placed between cylinders, the frame of
which is supported on the cylinder to be machined and on some
other cylinder. Bearing devices include rotating balls, roll
wheels, or slide blocks so that the device may move supported
on the cylinders, and, in principle, the cylinders may also
rotate during machining. The machine tool, e.g. a grinding
machine, has been movably fastened to the frame, and the
machining is controlled by controlling the position and move-
ment of the machine tool in relation to the frame. The problemof this solution is that the roughness and defects in form of
the stop surfaces impede the movement of the apparatus, and,
on the other hand, make the machining more difficult and
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impair its quality despite the fact that one has tried to
prevent this by making at least some of the bearing devices
flexible.
The patent SE 501250 again discloses an apparatus for machin-
ing cylinders, comprising a frame support placed against the
cylinder surface to be machined by rollers or other similar
parts, and a pressure plate in form of another cylinder placed
on the said surface by pressure cylinders. A machine tool,
such as a machine blade, is movably attached to the frame
support. When using the apparatus, the pressure plate is
pressed against the stationary other cylinder, and the cylind-
er to be machined is rotated. The machining can only be car-
ried out at one place at a time by guiding the movable machine
tool within an area in which it is able to move in a fixed
frame support. The drawback of the apparatus also is that the
machine tool is placed in relation to the frame support,
which, supported by the rollers, follows the surface to be
machined and thus also its roughnesses and defects in form.
The patent US 2942385 again discloses a machine tool which ~ay
include one or more ~earing surfaces leaning against the stop
surfaces, and grooves to which a pressure medium is fed so
that a pressure compensating the weight of the device is
generated against the bearing surface and the stop surface,
and the apparatus may easily be moved on the stop surface or
surfaces. This enables the machine tool to be easily moved on
the stop surface or surfaces. No solution for controlling the
machine tool is presented.
3~
It is the object of the present invention to provide an ap-
paratus for machining surfaces with which the draw~acks of the
known solutions may be avoided and which may be used in a
versatile way to repair and grind various surfaces on site.
The object is achieved by an apparatus of the present inven-
tion for grinding surfaces, comprising a frame, machine tools
attached to the frame, and several bearing elements attached
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to the frame which include a bearing surface and equipment to
be placed against the surface to be machined and/or some other
stop surface for forming an air cushion or a liquid cushion
between the bearing surface and the stop surface; it is char-
acteristic of the apparatus that it includes guidable adiust-
ing equipment in the attachment to the frame of at least one
bearing element for the control of machine tools in order to
adjust the position of the said bearing surface in relation to
the control carried out.
Further, the apparatus advantageously comprises control equip-
ment coupled to the adjusting equipment for controlling the
adjusting equipment.
In addition, the apparatus advantageously includes e~uipment
for moving it along the surface to be machined, and in a form
developed further, it also includes e~uipment for registering
the position of the apparatus and for controlling its move-
ment.
In an advanced embodiment, the apparatus comprises program-
mable guide equipment coupled to the ad~usting equipment of
the bearing elements, to the position registration and control
equipment in order to control the movement of the apparatus
and the position of the bearing elements in relation to the
frame in accordance with the programming.
An advantage of the apparatus of the present invention, when
compared with prior art devices is, first, that because of the
air or liquid cushions placed between the surface parts of the
bearing elements and the bearing surface, the apparatus can be
easily moved. Due to air or li~uid cushions and because, in an
advantageous realization, the bearing surfaces are relatively
large, the apparatus does not follow small roughnesses or
defects in form or disturbing vibrations of the surface to be
machined or of the other stop surface. Grinding or other
machining may be initiated on the damaged piece. Compared with
prior art solutions, the work may in many cases be started
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very fast by first installing the measuring devices and then
making the repair program, whereafter the work may be in-
itiated. The apparatus of the invention may also be driven on
a very dirty surface or on a surface of otherwise poor
quality. Thus, it is first possible to remove fast the worst
dirt and roughnesses, and thereafter prepare a program for the
final repair. The bearing surface may be arranged in relation
to the apparatus frame so that the frame extends over the
bearing elements at the ends of the apparatus, thus enabling
the machine tool to carry out the machining procedure all the
way to the edges of the surface to be machined. By equipping
the bearing elements with adjusting equipment, when necessary,
and by e~uipping the apparatus with necessary control equip-
ment, an apparatus is provided with which machining may be
controlled mainly by controlling the frame movement. If it is
desirable to readjust the surface to be machined to one direc-
tion or other, the apparatus is guided to follow a line reali-
zing the readjustment. Also control of machine tools is easily
added to the control. In order to repair a guiding surface or
a similar surface on site, a solution tailored in some way or
other is generally needed. The realization and operation of
the apparatus of the present invention make it possible to
easily tailor an apparatus to suit special needs from certain
basic components.
The present invention and its various embodiments are next
described in more detail referring to the enclosed drawings,
in which
Fig. 1 is a schematic view of an embodiment of the apparatus
of the invention;
Fig. 2 is a schematic view of another embodiment of the inven-
tion;
Fig. 3 shows a possible realization of a bearing element of
the present invention seen from the front and partially in
section;
Fig. 4 is a schematic sectional view of a possible realization
of the adjusting equipment of a bearing element seen from the
front;
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Fig. 5 is a sectional side view of the adjusting equipment of
Fig. 4 along the line A-A;
Fig. 6 shows a possible realization of a bearing ele~ent as a
simplified and schematic sectional side view;
Fig. 7 is a schematic view of a possible realization of a
baring element seen from below;
Fig. 8 shows a part of an embodiment of the invention of Fig.
1 seen from the front;
Fig. 9 is a schematic view of an embodiment of the invention
shown in Fig. 1, including control equipment and accessories,
adapted to be used in the repair of paper machine rollers; and
Figs lO(a) and lO(b) show another embodiment of an apparatus
of the present invention.
Figure l is a schematic view of an embodiment of an apparatus
of the present invention for repairing paper machine rollers.
The apparatus is placed between rollers Tl, T2 and T3. The
apparatus includes frame 1 intended for these applications,
and projections 2 extending between the rollers; bearing
equipment 11, 12, 13, 14, 15 and 16 supporting on the various
roller surfaces have been attached to the projections in a way
shown in the figures. At the same time, fastening devices 18
advanta~eously act as adjusting equipment in a way shown later
in connection with Figures 3 - 5, with the help of which the
position of the bearing equipment may be guided in relation to
the frame 1. Bearing surfaces 20 of the bearing equipment,
which are shaped to follow the cylinder surfaces, lean against
the roller surfaces T1, T2 and T3 acting as stop surfaces. In
an apparatus of the present invention it is essential that air
or li~uid, such as water or cutting fluid, is fed under suit-
able pressure between the bearing surface of the bearing
equipment and the stop surface. This makes it possible for the
apparatus to move lightly and steadily on the stop surfaces.
If the stop surface is uneven, a thin sheet metal, for ex-
a~ple, may be placed on it in order to ease the control of themovement and adjustment of the apparatus. In such embodiments,
the basic frame of the apparatus may be constant, but both the
projections 2 and the bearing equipment attached to these will
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generally have to be tailored to suit the subjeGt of machin-
ing. On the other hand, standard measurements are used, for
example, in paper machine rollers, thus making it possible to
use the same assembly for repairing many objects.
The machine tool used in this embodiment is a grinding car-
rier, which is shown schematically and in simplified form in
~igure 1. Frame 3 of the grinding carrier is attached to the
apparatus frame 1. An abrasive band 7 is rotated by a drive
wheel 4, and the band passes through two other wheels 5 and 6.
In this case, the apparatus is used to grind the roller sur-
face T3. The construction and operation of the grinding car-
rier is described in more detail later referring to the ~igure
8.
Figure 2 shows an embodiment of the apparatus of the present
invention, intended for the simultaneous cleaning grinding of
several rollers. The apparatus is otherwise similar to that of
Figure 1, but two other grinding carriers have been attached
to the corresponding projections 2 of the frame 1 for grind-
ing the roller surfaces T1 and T2. The grinding carriers are
completely identical with the carrier in Figure 1, and same
reference numbers are used to indicate same parts.
A possible realization of the bearing equipment and its fas-
tening and adjusting elements is next described more closely
referring to the Figs 3 - 7. Figure 3 is a schematic view of
the bearing equipment 11 seen from the front, and at the left
end it is shown in section in order to illustrate certain
3~ details. It is advantageous to ma~e the bearing elements large
enough so that the bearing surfaces would be able to carry the
apparatus on the air or liquid cushions to be formed under-
neath. Between the bearing surface 20 of the bearing element
and the stop surface, on which the bearing element in question
is supported, for example, air, water, cutting fluid or some
other suitable liquid may be led in a way shown by arrows in
Figure 3 for forming a cushion. Air or liquid may be used to
simultaneously cool the surface.
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The bearing surface 11 in Figure 1 is longitudinal in shape,
and it is attached to the projections 2 of the frame by cor-
responding fastening and adjusting elements 18 near both ends.
The adjusting elements 18 may be used to adjust the distance
between the bearing element 11 and the projection 2 in a way
illustrated by arrows drawn beside them. The adjustment is
carried out by stepping motors 25 which receive their control
from interface 26.
Figs 4 and 5 illustrate in more detail a possible realization
of the adjusting equipment. A cylindrical part 18 is fitted
into a corresponding aperture in the projection 2. Its upper
part comprises crossing runners 35 and 36, the latter of which
includes an axis 31 supported and pivoted on the projection 2
at places 32 and 33. An eccentric 34 placed in the runner 35
is attached to the axis. While rotating clockwise (Fig. 5),
the eccentric gliding against the bottom 37 of the runner 35
pushes the part 18 downwards and the bearing element 11 away
from the projection 2. While rotating anti-clockwise, the
eccentric allows the part 18 to glide upwards, and the part 18
is moved to this direction by the pressure acting on the
bearing surface. The axis is rotated by the stepping motor 25
(Figure 3), the control led to which determines the position
of the eccentric 34 and thus the adjusting element 18. A
chamber 38 is arranged in the lower part of the element 18, to
which a channel 39 leads. With the help of li~uid or air led
to the chamber, fine adjustment or elasticity may be provided,
thus improving the operation of the bearing element. It has to
be noted that the adjustments needed are generally very small,
either under one millimetre or in the range of a few mil-
limetres, at the most 10 millimetres.
The construction with which the air or liquid cushion is
arranged below the bearing surface is next described more
closely referring to Figs 3, 6 and 7. As illustrated in Figure
7, the bearing surface 20 is advantageously divided into
several part~ of areas 41, each having an own unit 24 as shown
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in Figure 3. The idea is that the pressure or amount of air or
liquid may be adjusted separately in various areas. Separately
adjustable areas may naturally also be formed in the lateral
direction of the bearing element. Each area 41 of the bearing
surface 20 comprises several extensions 27, each receiving an
air or li~uid duct 23 from a unit leaning against the area. It
is the purpose of the extensions to intensify the formation of
air or liquid cushions.
Figures 3 and 6 illustrate the advantageous realization of the
bearing element so that it comprises a frame part 22 and a
surface part 21 detachably attached to it, the surface part 21
including a suitable surface 20 with extensions 27, and addi-
tionally ducts 23 connecting the extensions 27 of each area 41
to the unit 24. The frame part 22 may, for example, be made of
aluminium, and the surface part 21 of suitable plastic
material. Manufacturing materials may include all suitable
metals, plastics, or composite materials.
As illustrated in Figure 3, an elastic flange 28, for example,
of rubber, is placed to surround the bearing element. It is
needed, especially, if liquid is used to form the cushion. The
flange acts as a seal on the edges of the bearing element, and
helps the formation of the cushion pretending the li~uid from
splashing as it is fed under pressure below the bearing sur-
face. The liquid discharging below the bearing surface is
collected to a space 29 formed on the flange 28 which may
include suction for removing the liquid in as controlled a way
as possible.
Figure 8 illustrates the upper part of the apparatus of Figur-
es 1 or 2 seen from the front, from the side of the bearing
element 12, illustrating especially a possible realization of
the grinding carrier and its operation. The bearing surface 20
of the bearing element 21 faces the viewer, and the bearing
element 11 may be seen behind it, the said element 11 being
attached to the frame projections 2 by fastening and adjusting
elements 18. The frame of the grinding carrier comprises, on
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the one hand, a supporting arm extending to the outermost
wheel G, and, on the other hand~ a part attached to the ap-
paratus frame 1 carrying the drive wheel 4 and a third wheel
5. A driving motor 8 rotates the drive wheel 4 and thus the
band 7 on the wheels 4, 5 and 6. The grinding carrier is able
to move in the longitudinal direction of the apparatus along
guides 46. The movement is carried out by ball screws 42
driven by the driving motor 9 through cogwheels 43 and cogged
belt 44. As can be seen from the figure, the bearing elements
11 and 12, and the attachment and movement of the grinding
carrier is arranged so that it is possible for the grinding
carrier to move further than the extent of the bearing ele-
ments. This enables the machining of the whole surface all the
way to the edges so that the bearing elements still remain
within the surface area. The grinding carrier may also include
equipment for adjusting the tightness of the band, and equip-
ment for guiding the abrasive band in relation to the surface
to be repaired and the apparatus frame.
The grinding carrier may vary in many ways within the scope of
the present invention. There may, for example, be more wheels
guiding the abrasive band arranged in a way that two nearby
wheels press the abrasive band against the surface to be
ground, the grinding being carried out by the part of the band
tightened between said wheels. When necessary, the final
grinding may be carried out using an ending band ~y placing
the band on a wheel or reel, and shifting it to another reel
while grinding. Also in this case, the band may be led through
several wheels, and it can simultaneously be used for grinding
several surfaces at a time.
Figure 9 is a schematic view of the apparatus of the present
invention with control equipment and accessories, and adapted
to be used in the repair of paper machine rollers, the ap-
paratus being arranged between the rollers in accordance withFigures 1 and 2. The apparatus 50 illustrated very schemati-
cally moves between the rollers, of which only the rollers T1
and T2 are shown, on the bearing e~uipment, of which the
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bearers 11, 12, 15 and 16 are schematically shown. The ap-
paratus is equipped with a grinding carrier 9. The apparatus
is movable with the help of a cogged belt 5g fastened to it.
The cogged belt is driven by a stepping motor 57, the belt
being conveyed through sheaves and jockey pulleys 58. The
longitudinal position of the apparatus can be precisely set
and defined by the stepping motor and its control. The frame
of the paper machine is illustrated in the figure with refer-
ence number 67, and the reference number 66 refers to an
auxiliary frame 66, on which a support beam 64 is supported.
For controlling the apparatus, the assembly comprises a laser
transmitter 52 and receiver 53 which are used to measure the
so-called neutral line. Correspondingly, the apparatus in-
cludes a measuring unit 55, measuring the travelling line of
the apparatus in relation to the neutral line. The operation
of the apparatus and of the whole assembly is controlled by a
computer or a programmable logic 51. The supply of energy and
the input of data is carried out via a cable assembly 56. The
wire and cable asesmbly is connected to a terminal carrier 65;
the assembly moves in synchronization with the terminal car-
rier, and it is carried by the supporting beam 64. Also tubes
needed for the pneumatically or hydraulically operating parts
of the apparatus may be arranged in the same connection. From
the terminal carrier 65, the connections are led further to
the apparatus 50. The figure also illustrates a collector tray
60 for cutting or cooling fluid, which may be a tarpaulin
stretched on wire cables. A pump 61 transfers the liquid back
to the repair apparatus 50 through a filter 62 and a pipeline
63.
Next it is described, how the apparatus of the present inven-
tion may be used and controlled in an embodiment illustrated
in Figures 1 and 9, where the apparatus is used for smoothing
grinding of the roller surface T3. Before the repair procedure
is initiated, the so-called neutral line is determined for the
surface T3. The neutral line is a line parallel to the
straight line between the midpoints of rotation of the support
bearings; the line may be set, as in Figure 9, by a laser beam
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54 guided through the measuring unit 55 in the apparatus.
Next, the distance of the neutral line from the level of the
surface to be repaired is determined at both ends of the
surface. Thereafter, the travelling line of the apparatus is
determined, i.e. the position of the apparatus in relation to
the neutral line is measured as the apparatus is driven from
the one end of the roller to the other. The idea is to drive
the apparatus first along the roller surface Tl on the bearing
elements 14 and 15 so that these are not adjusted. Upon grind-
ing, the travelling line of the apparatus is in outline knownwithout adjustment, and the apparatus is guided in vertical
direction mainly by bearing elements 14 and 15, and in lateral
direction by bearing elements 11 and 12 by guiding the posi-
tion of their bearing surfaces 20 in relation to the frame as
described above. The aim of the adjustment is, first, to ~ake
the apparatus follow the neutral line as closely as possible,
and, secondly, to also keep the apparatus parallel to the
neutral line as closely as possible. As is stated above, also
the grinding carrier is advantageously equipped with equipment
for guiding the abrasive band in relation to the surface to be
repaired. In addition, the apparatus advantageously includes
measuring equipment which measure the distance from the sur-
face to be repaired using a so-called three-probe measurement
method. When the distance of the apparatus frame and the
measuring equipment from the neutral line is known, and, on
the other hand, when the distance measured by the measuring
equipment from the surface to be repaired is known, the repair
procedure may be controlled so that exactly the desired form
is provided on the surface.
The apparatus of the present invention and its use may vary
in connection with the embodiments described above. For ex-
ample, in the case illustrated in Figure 2, where several
roller surfaces are cleaned simultaneously, no exact control
is needed to use the apparatus, but it is sufficient to guide
all abrasive bands against the surfaces to be cleaned. When
repairing rollers with the help of arrangements described
above, it is essential that the roller to be repaired has to
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12
rotate. Other rollers may either rotate or be stationary,
depending on the e~bodiment. The apparatus may be used to
lapping grinding of the roller in a way departing from the
normal lapping grinding so that instead of rotating the abras-
ive band, the roller to be ground is rotated with great speed,
e.g. with a surface speed of 100 m/min. When repairing grooved
rollers, lathe tools may be provided to repair the grooves.
Figures 10(a) and 10(b) illustrate an example of another
em~odiment in accordance with the present invention. Here,
guiding surface 88 of a beam 85 supported on the floor 87 by
a ~ase 86 is repaired. The bearing equipment 73 are supported
on the floor surface, and they are attached to the parts 72 of
the frame 71 with fastening and adjusting elements 74 which
are controlled by stepping motors 75. The grinding apparatus
consisting of a frame 79,a grinding head 77, a grinding tool
78 and an electric motor 80 rotating the grinding head, is
controlled by a stepping motor 82 and a screw 81. The ap-
paratus may include measuring equipment and control equip~ent
which, however, have not been included in the description for
the sake of simplicity.
The apparatus of the present invention may advantageously be
used for many objects especially when it is necessary to
repair various surfaces on site, for example in connection
with scheduled maintenance of massive industrial and energy
production facilities. One embodiment may, for example, be
directed to interfaces of power plants, the repair of which is
very difficult with conventional methods. The surface to be
repaired may, for example, be dozens of metres long, and for
the repair of such a surface an apparatus of several metres
long may be tailored, which, for example, moves on the floor
in a way illustrated in Figure 10. When repairing guiding
surfaces, the apparatus may, for example, rest merely on the
guiding surface itself, or also on other surfaces of the guide
beam. The apparatus may also ~e adapted for the repair of
vertical surfaces with the help of suitable bearing and guid-
ing surfaces, and by moving the apparatus suspended on a ca~le
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wire.
The control of the apparatus may vary to a large extent in
accordance with the embodiment. If the apparatus moves on the
bearing surfaces with sufficient precision, it is possible to
- realize only a repair programme with which the repair is
carried out. If the mere repair programme is not sufficient,
the apparatus itself may be guided along the neutral line by
the measuring equipment, and additionally, also the machine
tool or tools may be controlled on the basis of measurements
continuously provided by the measuring equipment. Also the
feed of air or liquid used in the formation of the cushion may
be programmed either according to each bearing equipment, or,
when necessary, separately in the area of every bearing equip-
ment. As is already stated above, the control may also beconducted in a simple way, in the simplest form completely
manually.
It is obvious for those skilled in the art that the bearing
equipment, their attachment, and the adjusting equipment
related with the attachment may be realized in many various
ways. The amount of fixing points may be determined according
to needs, and there are many alternative ways to carry out the
adjustment. For example, the adjustment may be realized as a
wedge, screw or toothed bar solution, and there also are other
alternatives for the adjustment control besides the stepping
motor. The control may include, for example, measurement and
sensor solutions, and feedback solutions.
It is essential for the invention that the machine tool
operates on the bearing equipment and on the air or liquid
cushions formed underneath, and that the apparatus may be
controlled and adjusted in relation to the bearing elements
and their stop faces by the adjusting equipment in connection
with said bearing elements. The thickness of the air or liquid
cushion may vary from a few hundreths of a millimetre to, for
example, 2 - 3 millimetres. The positive pressure needed in
the cushions is relatively low. For example, if in the case
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illustrated in Figures lO(a) and lO(b), the bearing elements
are 1 m long and 0.2 m wide, their joint area is 4000 cm2, and
a positive pressure of 0.1 kp/cm2 would be sufficient to carry
an apparatus of 400 kg.
The invention may vary within the scope of the enclosed patent
claims.
