Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF MANUFACTURING SHEETS BASED ON HYDRAULIC
BINDER, PRODUCTION LINE FOR PRODUCING SUCH SHEETS AND
APPARATUS FOR MAKING AN IMPRESSION
The present invention relates to a method of
manufacturing sheets based on hydraulic binder, in
particular sheets of plasterboard with feathered edges,
to a production line for producing such sheets, and to
an apparatus, particularly for making an impression in
a preform based on hydraulic binder.
In a production line for producing sheets based on
hydraulic binder, the sheets are generally obtained by
cutting a preform based on hydraulic binder into
determined lengths.
Use is therefore generally made of a cutting system
made up of a wheel placed on the top of the preform and
driven in rotation by the movement of this preform. The
wheel is graduated and coupled to a counter which
actuates the cutting device once the desired length for
the sheet is reached.
The wheel and the counter are usually situated at the
downstream end of the production line, a short distance
away from the cutting device, this being so as to avoid
the phenomena of lengthening or shortening of the
preform.
The invention is aimed at proposing an alternative to
this wheel/counter system.
More specifically, the invention relates to a method
for manufacturing sheets based on hydraulic binder from
a preform intended to be cut, this method comprising
the steps of:
1) making at least one mark on a facing material of
the preform (5);
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2) detecting the mark; and
3) sending an actuating signal to a device for
cutting the preform.
A method such as this in particular has the advantage
of allowing the length of the sheet to be determined at
the time of the forming of the preform.
Furthermore, it allows other operations, such as the
introduction of a lath under the preform, the making of
an impression in the preform or the marking of the
sheet so that the mark is centered in the lengthwise
direction, to be initiated.
Such a method also has the advantage that it can be
used in the production of sheets based on hydraulic
binder with feathered (tapered) edges.
According to one embodiment of the invention, the mark
is already detected before step 2) and an impression is
made in the preform.
According to another embodiment of the invention, the
mark is already detected before step 2) and a lath is
introduced under the preform, the composition is left
to set, then the lath is removed.
According to yet another embodiment of the invention,
the mark is already detected before step 2), an
impression is made in the preform and a lath is
introduced under the preform, the lath then
advantageously being introduced after the impression
has been made and where the impression has been made.
Another subject of the invention is a production line
for producing sheets based on hydraulic binder from a
preform, this line comprising:
a) in an upstream zone of the production line, means
of marking a facing material of the preform;
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b) in a downstream zonI e of the production line means
of detecting a mark made by the marking means;
c) a cutting device; and
d) actuating means for actuating said cutting device
after receiving a. detection signal from the
detection means.
According to one embodiment of the production line for
Producing sheets based on hydraulic binder according: to
the invention, there are :prov:ided` additional meats of
detecting the mark, means of making an impression in
the preform. and/or a device for introducing laths under
they preform,. additional actuating means for actuating,
after receiving a: detection signal from the additional
1 detection means,, said means of making an impression in
the preform and/or said means of introducing lath
utxder the preform.
According to an. advantageous alternative form of this
20 embod nt, the additional actuating means anticipate
that each lath be introduced substantially where an-
i;mpres5ion: has been made or opposite the place where an
impression= has been made.
According to another aspeot of. the invention, there is
proposed an apparatus in particular allowing the peaking
of an impression or reservation in a. prefo based on
hydraul is binder
30 ti On this subject, mexican Patent No 4 781 SSA describes an apparatus
intended for. manufacturing sheets of
plasterboard with recesses. It therefore proposes the
making, an. a: preforms intended to be cut to give sheets
of plasterboard, of recesses using a drum comprising
3.5 bosses: (see its particular figur I of that patent)
The:' depth of: the recesses is therefore determined by
the size of the,, boasses. Thus, to change the depth
and/or: the shape of these :recesses, it will be
necessary to. replace the drum with another drum
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having bosses. of a diffexerit size and/or shape.
............. ...
In :;Americanpatent No.. 2 991 82-4, i ressions
are made in a preform intended to be cut to give sheets
of plasterboard, by means (see In ;particular: figure: 1
and:..colu ., lines; 29 to. 43 of that patent) of a hai d
rotating: around two rollers and having a
Projection. The preforcct is then cut in:the middle of
the a.a -ress-ions as as:: to pxoduce sheets with feathered
edges,
,In this case : too., to :change the s .;ze and/or shape of
the impressions, it would be nene.ssary to replace the
band with anther band having projections of
different size and/or shape. invention., is therefore aimec~ at solving the
probleu,
of making mpres iGx s in 'a prefo while at the sa
time offering the possibility of changing the size
2C and/or shape of these. preset ns..qu ck y an >e ,
More specifically, :the. apparatus according. to the
invent ien corm ses at yeast
w a .frame
two. fi:rat pulleys supported at a first end of the
frame. a 0d two second: put eta; at a second ehd .of
the frame, the first pul1any. and ;second pull s
being in parallel planes, the pul=ley's facing each
other being identical;
two tran`smissio'i :belts wrapped respectively around
the first 'pulleys and the second pulleysi
at :.east: one wire fixed removably to the belts and
extending between these belts so that its
longitudinal Akio is parallel to the
as s oaf
rdt tion: of the pulleys....
:,Thus.., the :.n rent s n ;snakes it possible. sail f act,vx - +
produce :sheets based on tydrau ; z c binder with feathered
edges.
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Other features and advantages of the invention will now
be described in detail in the description which follows
and which is given with reference to the figures in
which:
figure 1 schematically and in perspective depicts
the upstream part of a production line for
producing sheets based on hydraulic binder
according to the invention;
- figure 2 schematically and in perspective depicts
the downstream part of a production line for
producing sheets based on hydraulic binder
according to the invention;
- figure 3 schematically and in perspective depicts
an apparatus for making impressions in the preform
based on hydraulic binder;
- figure 4 schematically and in section depicts the
assembly of a wire onto a chain link;
- figure 5 schematically depicts a wire gripper pin;
- figure 6 schematically and in a view from above
depicts a support piece mounted on a chain link;
- figure 7 schematically depicts the support piece
of figure 6, viewed from the front;
- figure 8 depicts a sheet that can be obtained
using the method according to the invention;
- figure 9 depicts another sheet that can be
obtained using the method according to the
invention;
- figure 10 illustrates an optional intermediate
step in a method of manufacturing sheets based on
hydraulic binder;
- figure 11 schematically and in perspective depicts
a device for introducing laths under a preform
based on hydraulic binder;
- figure 12 schematically and in a top view depicts
the device of figure 11;
- figure 13 schematically and in a side view depicts
the device of figure 11;
- figure 14 schematically and in a side view depicts
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an alternative form of the device of figure 11;
figure 15 schematically and in section depicts a
detail of the device of figure 11 illustrating the
introduction of a lath under a preform based on
hydraulic binder;
figure 16 schematically depicts part of a
production line for producing sheets based on
hydraulic binder according to the invention
comprising an alternative form of the apparatus
for making the impressions; and
- figures 17 and 18 schematically depict a pusher
and its receptacle, these being elements of the
apparatus for making the impressions of figure 16.
DETAILED DESCRIPTION OF THE INVENTION
METHOD ACCORDING TO THE INVENTION
Figure 1 shows an upstream part of a production line
for producing sheets based on hydraulic binder.
In the upstream zone of the line, a hydraulic binder
composition 2 is poured onto a facing material 1 and
generally covered with a second facing material 3. The
passage of the entity under the forming plate 4 gives a
preform 5 which moves, supported by a conveyor belt 7,
toward the downstream zone of the line where it is cut
transversely by a cutting device 9 generally consisting
of a roller equipped with a cutter (figure 2), to give
sheets.
The terms "upstream" and "downstream" refer to the
direction of travel of the preform 5.
The "upstream zone" is therefore intended in this
description to mean the part of the production line
situated near the forming plate 4.
The "downstream zone" is intended to mean the part of
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the production line situated near the cutting device 9.
The hydraulic binder composition preferably contains
plaster.
The facing materials 1 and 3 may consist of sheets of
paper, glass matting or any material known to the
person skilled in the art as being able to be used as a
facing.
According to the invention, marking means 300 are
provided, generally upstream of the forming plate 4, to
produce at least one mark, preferably on the facing
material 3 of the preform 5.
The mark is therefore generally made upstream of the
forming plate 4, that is to say before the preform 5 is
formed.
The mark may be produced by depositing a material such
as an ink on the surface of the facing material, so as
to make a spot, a line or any sign. The deposited
material may or may not be visible to the naked eye.
The size of the mark may vary widely.
The mark may also consist of a relief or recess made on
the surface of the facing material.
The marking means 300 may therefore consist of a piece
forming an inking stamp which is moved regularly back
and forth toward the facing material 3 as illustrated
by the double-headed arrow B. When the piece forming a
stamp comes into contact with the facing material 3 it
leaves a mark 301 on the face of this material.
As an alternative, it is also possible to use other
marking means 300 such as an encoder wheel coupled to
an inkjet device to trigger clean printing (indexing
the speed of the jet as a function of the rate of
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travel of the paper) at the desired frequency,
controlled by the person skilled in the art or the
operator.
Figure 2 also shows detection means 302 arranged above
the preform 5, at an appropriate point so that when a
mark 301 passes under them, they are able to detect it.
These detection means 302 are of course chosen
according to the type of the mark that is to be
detected. They may consist of a photoelectric sensor.
Thus, each time the presence of a mark 301 on the
preform 5 is detected by the detection means 302, a
detection signal is sent to actuating means (not
depicted) which then send an actuating signal to the
cutting device 9 so that the latter cuts the preform 5
to give a sheet.
According to an advantageous embodiment of the
invention visible also in figure 1, additional
detection means 303 are provided downstream of the
marking means 300, preferably in the upstream zone,
generally upstream of the forming plate 4.
These additional detection means 303 are generally of
the same type as the detection means 302 because they
need to be able to detect the mark 301.
Additional actuating means are then also provided to,
having received a detection signal from these
additional detection means 303, send an actuating
signal to an apparatus for making an impression or
reservation in the preform 5.
This additional detection of the mark 301 for making an
impression therefore takes place before the mark 301 is
detected in step 2) of the method which triggers the
cutting of the preform 5.
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The impression may be made by any means, for example by
following the teachings of American patents
Nos. 2 991 824 or 4 781 558.
As a preference, however, use is made of an apparatus
which will now be described in detail.
Making the impressions
The preferred apparatus for making the impressions is
depicted schematically in figure 3.
It comprises a frame 101 in the shape of an H but which
can easily be given numerous other shapes by the person
skilled in the art.
Supported on this frame 101 are, at a first end 104,
two first pulleys 102 and 103 and, at a second end 107,
two second pulleys 105 and 106.
The first pulleys 102, 103 lie in a first plane, the
second pulleys 105, 106 in a second plane and the first
plane is parallel to the second plane.
The pulley 102 and the pulley 105 are situated one
facing the other and are identical.
The pulley 103 and the pulley 106 are also situated one
facing the other and are identical.
The pulleys 102, 103, 105 and 106 can rotate about
themselves.
A first transmission belt 108 is wrapped around the
first pulleys 102, 103 and a second transmission belt
109 is wrapped around the second pulleys 105, 106.
The transmission belts 108 and 109 are identical. They
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are connected together by at least one wire 111.
This wire 111 is fixed removably to the first and
second belts 108, 109 and extends between these belts
5 108, 109 so that its longitudinal axis is parallel to
the axis of rotation of the pulleys.
Thus, when one of the pulleys, for example the pulley
102, turns, it drives the transmission belt 108 which
10 itself drives the other pulley situated in the same
plane as it (the pulley 103) and the wire 111. The
latter therefore moves in the path defined, on the one
hand, by the loop consisting of the belt 108 and, on
the other hand, as it is connected to the second belt
109, also by the loop consisting of the latter.
The symmetry of the apparatus according to the
invention therefore allows the axis of the wire 111 to
move in an elliptical path, its axis remaining
constantly parallel to that of the pulleys.
Provision may be made for two pulleys situated one
facing the other to be fixed on one and the same shaft.
The apparatus may also comprise means for driving the
rotation of at least one of the pulleys. These means
may possibly drive two pulleys by means of the shaft on
which they are mounted.
The wire 111 generally has a cylindrical shape, but it
may adopt a great many shapes among which mention may
be made of parallelepipedal, prismatic, etc. shapes.
It may be fixed for example by screwing to the
transmission belts so as to be able to be unscrewed and
replaced easily by another means of elongate shape.
According to a preferred embodiment of the invention,
several wires 111 are arranged parallel to one another
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along the transmission belts 108 and 109 (see
figure 3).
The pulleys are preferably sprockets and the
transmission belts chains able to collaborate with
these sprockets.
The wires may then be fixed in the way illustrated in
figure 4.
This figure 4 shows a wire 111 held on a chain link 112
by means of a support piece 113 and a wire gripper pin
114.
The latter, in the chain link 112, replaces one of the
roller bearing pins conventionally used.
The wire gripper pin 114 is shown in detail in
figure 5. It comprises, in order:
- a threaded end 115,
- a generally cylindrical and plain part 116 able to
be introduced into the roller of the chain link
112 to replace the roller bearing pin
conventionally used,
- a plain part also generally cylindrical and plain
117, of a diameter generally greater than that of
the part 116 and able to be introduced into the
hole 118 in the support piece 113 (see figures 6
and 7),
- a head 119, and
- a central bore 120 machined generally from the
head 119, able to extend as far as the part 116
and intended to house the wire 111.
The support piece 113 is visible in figures 4, 6 and 7.
It comprises the hole 118 able to collaborate with the
corresponding part 117 of the wire gripper pin 114 and
a bore 121 opening into the hole 118. This bore 121 is
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threaded so that a press screw 122 can be screwed into
it to compress the wire Ill present inside the hole 118
with a view to holding it firmly (see figure 4).
Thus, to fix a wire 111 to the chain link 112, the set-
up of figure 4 is achieved. To do that, all that is
required is for the part 117 of the wire gripper pin
114 to be introduced into the support piece 113, for
the normal roller bearing pin of the link 112 to be
removed, for the part 116 of the wire gripper pin 114
to be introduced along the axis of the roller, and for
the assembly to be tightened by screwing a nut 123 onto
the end 115 of the wire gripper pin 114, for the wire
111 to be introduced into the central bore 120 of the
wire gripper pin 114 and for it to be held there firmly
by screwing the press screw 122 into the threaded bore
121 until it effectively compresses the wire 111.
Of course the wire gripper pin 114 is mounted in such a
way that its head 119 is on the inside of the chain,
that is to say on the side facing toward the other
chain.
The support piece 113 preferably comprises two pairs
(hole 118, threaded bore 121), the spacing between the
axes of the holes 118 corresponding to the normal
spacing between the axes of the rollers of a chain link
112, so that two wires 111 can be held on the same link
112, as can be deduced from figures 6 and 7.
By thus having several identical support pieces 113 on
adjacent links, it is possible to align several wires
ill in parallel so as to constitute a means of elongate
shape.
In order for the apparatus which has just been
described to be able to be used in an optimum manner on
a production line for producing sheets based on
hydraulic binder, the distance between the transmission
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belts of this apparatus is at least equal to the width
of the preform 5. Thus, these belts and the pulleys lie
on each longitudinal side of the preform.
Furthermore, the apparatus is arranged in an
appropriate way so that when its transmission belts are
turning, its wire or wires 111 creates or create an
impression in the preform 5.
The apparatus may be above the preform 5, in which case
it creates the impression 12, or under the preform 5,
in which case it creates the impression 12bis visible
in figure 10.
For practical reasons, it is preferable for the
apparatus according to the invention to lie above the
preform 5.
The operation of the motor is adjusted so that the
transmission belts move at the same speed as the
preform.
Of course, it would be possible to anticipate two (or
more) apparatuses according to the invention, one
situated above and the other below the preform, so as
to create, respectively, an impression 12 on the top of
the preform 5 and an impression 12bis on the underside
of the preform 5 (see figure 10) , the underside of the
preform 5 being the side of this preform 5 which rests
on the conveyor belt 7.
The position of the impression 12 is not directly
connected to that of a mark 301, which means that an
impression 12 may or may not be made on a mark 301.
Likewise, the position of the impression 12bis is not
directly connected to that of a mark 301, which means
that an impression 12bis may or may not be made under a
mark 301.
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The position of the mark 301 and that of the impression
are advantageously chosen so that the preform 5 is cut
at an impression 12.
This then gives sheets 9bis with feathered transverse
edges 10 visible in figure 8.
If faced with an impression 12bis made on the underside
of the preform, the cutting device can be set to cut
the preform opposite the place where this impression
12bis has been made (that is to say on the other face
of the preform).
The preform is preferably cut approximately at the
middle of the impression 12 or 12bis.
Introducing laths under the preform
According to another embodiment, the additional
actuating means are able, after receiving a detection
signal from the additional detection means 303, to send
an actuating signal to a device for introducing laths
under the preform 5.
Thus, the method according to the invention supplements
a method of manufacturing sheets of plasterboard with
feathered (tapered) edges comprising the following
steps (see figure 1):
1) a hydraulic binder composition 2 is poured onto a
facing material 1 supported by a conveyor belt 7
so as to obtain a preform 5, then a lath 6 the
length of which is at least approximately equal to
the width of the preform 5 is introduced under the
preform 5;
2) the hydraulic binder composition 2 is left to set
2 and said lath 6 is removed;
3) the preform 5 is cut at the feathering 8 created
by the lath 6.
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The additional detection means 303 and the electronic
means therefore allow the lath 6 to be introduced under
the preform 5 after the mark 301 has been detected, by
sending an actuating signal to a device for introducing
laths 6 under the preform 5.
This additional detection of the mark 301 for
introducing laths 6 therefore takes place before
detection of the mark 301 in step 2) of the method
which triggers the cutting of the preform.
The position of the mark 301 is not directly connected
to the introduction of the lath 6, which means that a
lath 6 may or may not be introduced just under a mark
301.
This introduction of the laths 6 under the preform with
a view to manufacturing sheets based on hydraulic
binder with feathered edges will now be described in
detail with reference to figures 1, 2 and 8 to 15.
First of all, it is necessary to emphasize that
"transverse edges" in this description are intended to
mean the edges perpendicular to the direction of travel
of the conveyor belt in a production line for producing
sheets based on hydraulic binder. Such transverse edges
are also known as "sheet ends".
With reference to figure 1, it can be seen that, after
the preform 5 emerges from under the forming plate 4 or
from under the equivalent device used in the production
line (for example, a forming roll also known as a
master roll), a lath 6 is introduced between the
preform 5 and the start of the conveyor belt 7. The
distance between the forming plate 4 and the start of
the conveyor belt 7 is such that the preform 5 has not
yet had time to harden appreciably and is still very
plastic. Introduction is performed in such a way that
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the longitudinal axis of the lath 6 is substantially
perpendicular to the direction of travel of the
conveyor belt 7.
The lath 6 is then driven by the conveyor belt 7, like
the preform 5. The plaster composition 2 then sets and
hardens throughout the travel of the preform 5, denoted
by the arrows A.
As a preference, the lath 6 is removed before the
preform 5 is cut.
Thus, after a certain time, to which there corresponds
a distance covered by the preform 5 on the conveyor
belt 7 that the person skilled in the art knows how to
determine as a function of the speed of travel of the
conveyor belt 7 and of the time taken for the plaster
composition to set, the hardness of the preform 5 is
sufficient that the lath 6 can be removed without
deforming the preform 5 and without the plaster
composition 2 filling the space or feathering 8
(figure 2) left by the removal of the lath 6.
The lath 6 can be removed in any appropriate way. For
example, when the length of the lath 6 exceeds the
width of the preform 5, the lath 6 projects from the
preform 5, and it can then be removed quickly in a
direction substantially perpendicular to the direction
of travel of the conveyor belt 7, and away from the
latter. This removal action is illustrated by the arrow
B in figure 1.
The lath 6 may also be removed by causing this lath 6
to drop into the space between two constitute rollers
of the conveyor belt system which, in general, is not
continuous along the entire length of the production
line but is made up of several belts driven by rollers
between which there are gaps.
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After the lath 6 has been removed, the preform 5
continues to travel, still driven by the conveyor belt
7, and the plaster composition 2 continues to harden.
According to the invention and as can be seen in
figure 2, the mark 301 is then detected, in the
downstream zone of the production line, by the
additional detection means 302 which then trigger the
operation of the cutting device 9.
The position of the mark 301 and that of the feathering
8 are advantageously chosen so that the preform 5 is
cut at the feathering 8, preferably approximately at
the middle of this feathering.
This then gives sheets 9bis with feathered transverse
edges 10 visible in figure 8, the lengths of which are
defined by the distance covered by the conveyor belt
between two cutting operations, that is to say, in
general, by the distance covered by the conveyor belt
between two consecutive featherings 8. This sheet 9bis
therefore has two feathered transverse edges 10.
The size of each feathering 8 depends on the size of
the lath 6. The latter is generally a parallelepiped
generally of between 0.5 and 4 mm and preferably
between 1.5 and 4 mm thick. Its width is generally
between 5 and 20 cm and its length is at least
approximately equal to the width of the preform 5
(possibly reduced by the width of the longitudinal
bands (tapes) that might be present), but generally
greater so that it can be grasped for removal from
under the preform 5. Furthermore, it is desirable for
the lath 6 to be longer than the width of the preform
5, so that it projects with respect to the latter,
which may make it easier to remove.
The material of which the laths 6 are made is of little
importance, provided that it allows these laths to
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withstand the weight of the thickness of the preform 5
lying on top of each lath 6. It may therefore be made
of a plastic, wood, metal, etc., with good resistance
to wear and good stability over time.
As a preference, the method which has just been
described supplements a known method for manufacturing
sheets of plasterboard having two feathered
longitudinal edges. The latter method generally
anticipates the placement of a band, generally made of
plastic, and generally known as a tape, along each
longitudinal side of the conveyor belt 7. Such a method
is described for example in European patent application
No. 482 810.
This therefore makes it possible to obtain a sheet
based on hydraulic binder 11 as illustrated in figure 9
which, apart from its two feathered transverse edges
10, has two feathered longitudinal edges 25, namely
four feathered edges in total.
The length of the sheets of plasterboard manufactured
depends of course on the rate of travel of the conveyor
belt and on the frequency of the cutting operations.
The frequency of the cutting operations is generally
directly connected to the frequency with which the
laths are introduced, because in general the desire is
to obtain sheets with two feathered transverse edges,
and the frequency with which the laths are introduced
is a function of the detection of the marks 301 and
therefore of the frequency of the marking operations.
This way of manufacturing sheets with feathered edges
is very flexible because, in order to change the length
of the sheets manufactured, it is generally sufficient
simply to alter the frequency of the marking
operations, this frequency determining the frequency
with which the laths are introduced and the frequency
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of the cutting operations.
Combination of the making of impressions and the
introduction of laths
According to one particularly advantageous embodiment
of the invention, the method according to the invention
involves both making an impression 12 or 12bis in the
preform 5 and introducing a lath 6 under the preform 5.
The additional actuating means are therefore able,
after detection of a mark 301 by the additional
detection means 303, to send an actuating signal to the
means of making the impression 12 or 12bis and an
actuating signal to the device for introducing laths 6,
so as to introduce a lath 6 under the preform, to allow
setting to take place, then to remove the lath 6, as
explained above.
In general, the steps of introducing a lath 6 under the
preform 5 then of the hydraulic binder composition
setting and of the lath 6 being removed take place
after the step of making the impression in the preform
5.
The impression is preferably made either opposite the
place where the lath 6 is to be introduced (impression
12) or at the place where this lath 6 is to be
introduced (impression 12bis).
That makes it possible to compensate for localized
additional thicknesses which may possibly be formed in
the preform 5 because of the displacement of material
when the lath 6 is of significant size.
It is also possible, with a view if necessary to
attenuating local additional thicknesses, to anticipate
the presence of a smoother 4bis of conventional type
(visible in figure 1) downstream of the place where the
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lath 6 is introduced.
PRODUCTION LINE FOR PRODUCING SHEETS BASED ON HYDRAULIC
BINDER
The production line for producing sheets based on
hydraulic binder according to the invention is
preferably a production line for producing sheets based
on hydraulic binder with feathered edges.
Such a line may comprise a device for introducing laths
and/or means for making impressions.
A production line for producing sheets based on
hydraulic binder with feathered edges equipped with
means or with a device for introducing laths 23 under
the preform 5 will first of all be described in detail
with reference to figures 1, 2 and 8 to 15.
Device for introducing laths under the preform
Referring to figure 11, it is possible to see the
upstream zone of a production line for producing sheets
based on hydraulic binder, comprising a device for
introducing laths under the preform.
This device comprises a laths magazine 20 formed of a
horizontal rectangular surface 21 from the corners of
which there rise vertically and in parallel four
bracket-shaped angular pieces 22 facing toward each
other, so as to flank a stack of laths 23.
The size of this laths magazine 20 is such that it can
store a great many laths 23 (see also figures 12 and
13).
The horizontal surface 21 of the laths magazine 20 is
supported on legs 24.
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At the first lath 23, that is to say the one at the
very bottom of the pile, there are, arranged in
parallel, two rams 26 which are oriented in such a way
as to extract the first lath 23 from the pile by
pushing it and causing it to slide toward an inclined
plane 27 consisting of a downwardly inclined surface 28
and of a rim 29 at its lower part to retain the lath
which has just been extracted and guide it later.
On the transverse side 30 of the inclined plane 27,
that is to say on the opposite side to the conveyor
belt 7, a ram 31 is arranged parallel to the
longitudinal axis of the inclined plane 27 so that
actuation of this ram 31 can give an impulse to the
lath which has just been extracted from the laths
magazine 20. The lath thus propelled can therefore
move, sliding parallel to the longitudinal axis of the
inclined plane 27, the rim 29 of which guides it,
toward a second inclined plane 22 in the continuation
of the first inclined plane 27, on the opposite
transverse side to the side 30. This second inclined
plane 32 also consists of an inclined surface 33
equipped with a rim 34 at its bottom. It further
comprises a stop 35 on its opposite end to the ram 31,
this stop generally consisting of a pneumatic damper
and being intended to end the movement of the lath
propelled by the ram 31.
The rim 34 is equipped with openings 36 facing which
there are two rams 37 oriented in such a way as to
propel the lath positioned on the second inclined plane
32 toward the top of the inclined surface 33.
The first inclined plane 27 and the second inclined
plane 32 are supported on legs 38 and 39 respectively.
According to an alternative form visible in figure 14,
a flat surface 40 is provided parallel to the surface
23, between this surface and the first inclined plane
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27, to horizontally support a lath extracted from the
laths magazine 20 before it descends along the inclined
surface 28 of the first inclined plane 27.
Thus, as can be seen in figure 15, the height of the
legs 24, 35 and 36 is chosen so that a lath positioned
on the second inclined plane 32 lies at a lower height
than the preform 5.
In general:
the longitudinal axis of the rim 34 of the second
inclined plane 32 is perpendicular to the
longitudinal axis of the conveyor belt;
the means 32, 33, 34, 35 for supporting the
displaced lath lie facing the start of the
conveyor belt 7; and
the inclined surface 33 of the second inclined
plane 32 is adjacent to the conveyor belt 7.
The length of the second inclined plane 32 is at least
equal to that of the lath 23, that is to say at least
equal to, and preferably greater than, the width of the
preform 5.
Thus, as can be understood by referring to figure 10,
when the rams 37 are actuated, the lath on the second
inclined plane 32 is pushed up toward the top of the
inclined surface 33, that is to say toward the conveyor
belt 7 and the preform 5, and finds itself wedged
between these and driven along by them.
The difference between the length of the lath and the
width of the preform 5 allows the lath to be grasped
and removed once the plaster composition has hardened.
The production line according to the invention
generally comprises electronic means which control its
operation and, as necessary, allow the performance of
various operations to be slaved to one another.
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These electronic means may make provision that, after a
lath has been introduced under the preform by actuation
of the rams 27, the ram 31 is actuated to introduce
another lath onto the second inclined plane 32, then
the rams 26 are actuated to introduce another lath onto
the first inclined plane 27, and so on.
As explained hereinabove, the electronic means are able
to send an actuating signal to the device for
introducing the laths 23 after receiving a detection
signal from the additional detection means 303.
Thus, the frequency with which the laths are introduced
under the preform is determined by the frequency with
which the marks 301 are made on the facing material 3
of the preform 5.
Alternative form of the apparatus for making
impressions
A production line for producing sheets based on
hydraulic binder with feathered edges equipped with an
apparatus for making impressions as has been described
in general hereinabove will now be described.
Figure 16 represents the upstream zone of such a line
comprising an alternative form of the apparatus for
making impressions that can be seen in profile in this
figure.
According to this alternative form, the apparatus
comprises four first sprockets 201, 202, 203, 204
supported by a frame 205 and with, wrapped around them,
a chain 206 made up of links of which some, the links
207, each support two wires, in the way indicated in
conjunction with figure 2.
This apparatus is symmetric with respect to a vertical
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plane aligned with the direction of travel of the
preform 5. Thus, the wires held on the links 207 extend
transversely with respect to the preform 5 as far as a
second chain, identical to the chain 206, and wrapped
around second sprockets identical to the first
sprockets 201, 202, 203, 204.
The apparatus is equipped with an electric motor 209
driving the rotation, via a belt 211, of the shaft 210
on which the sprocket 203 and its symmetric sprocket
are mounted. The turning of these sprockets drives the
rotation of the chain 206 in the direction indicated by
the arrow D.
This preform 5 is obtained in a known way by
introducing hydraulic binder slurry in the direction of
the arrow E between the first facing material 2 and the
second facing material 3 and passing the entity between
the upper 214 and lower 215 forming plates of the
apparatus.
The distance between the sprockets 201, 202, 203, 204
and their symmetric sprockets is at least equal to the
width of the preform 5 so that these sprockets do not
touch this preform 5.
The apparatus according to the invention is fixed at an
appropriate height so that when the production line is
operating, the movement of the chain 206 driving the
movement of the wires connected to the links 207, these
wires pass through the forming plate, that is to say
between the plates 214 and 215, and project downward
with respect to the upper plate 214. The space occupied
by these wires between the upper plate 214 and the
second facing material 3 therefore results at this
point in a feathering of the thickness of the preform
5.
It goes without saying that the operation of the motor
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is adjusted in such a way that the chain 206 moves at
the same speed as the preform 5. The wires therefore
accompany the preform 5 over a few centimeters and,
when they separate from it to return, rotating about
the sprocket 204, they leave an impression in the upper
part of the preform 5.
As explained above, the electronic means of the
production line are able to send an actuating signal to
this apparatus for it to make each impression after
receiving a detection signal from the additional
detection means 303.
Combined use of an apparatus for making impressions and
of a device for introducing laths
According to one particularly advantageous embodiment
of the invention, the means for making impressions
collaborate with the device for introducing laths under
the preform 5 (consisting of the means 20 to 22 and 24
to 39 described hereinabove in conjunction with
figures 11 to 15).
The additional actuating means are therefore able,
after the additional detection means 303 have detected
a mark 301, to send an actuating signal to the means of
making the impression 12 or 12bis and an actuating
signal to the device for introducing laths 6.
Although it is possible to use any appropriate means
for making the impressions, use is preferably made of
the apparatus which has just been described with
reference to figure 3 and, more preferably still, of
the alternative form described with reference to
figure 16.
This alternative form is then advantageously arranged
upstream of the device for introducing the laths.
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The electronic means therefore preferably calculate the
precise moment at which they need to send the actuating
signals to the apparatus for making impressions and to
the device for introducing laths, so as to synchronize
their operation so that the lath is introduced in an
impression 12bis lying on the underside of the preform
5, or alternatively, if the impression 12 is on the top
face of the preform 5, substantially opposite this
impression 12.
According to a preferred embodiment of the
collaboration between the apparatus for making
impressions and the device for introducing laths under
the preform, the laths 23 are introduced under the
preform 5 partly by the apparatus for making
impressions.
As an alternative, this mechanical link between the
apparatus for making impressions and the device for
introducing laths can be replaced by a combined
apparatus grouping together both means for making
impressions and means for introducing laths.
This makes it possible to obtain easy and perfect
synchronization of said apparatus and said device,
resulting in the laths being introduced at the best
time, or, in other words, at the best position relative
to the preform 5.
In order to obtain such synchronization, the rams 37
(figure 15) are replaced by pushers 217 which can fit
into the openings 36 in the rim 34 (figure 11).
The chain 206 is then provided with a pushing finger
216 which is fixed on the outside of the chain 206,
that is to say on the opposite side to the side on
which the wires are located. This pushing finger 216
has the function of striking and moving the pusher 217
as the chain 206 turns. It may be fixed to a link of
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the chain 206 for example in place of a roller bearing
pin of this link.
In figure 16 it is possible to see the inclined surface
33 of the device for introducing the laths (figure 15)
and its rim 34 and a lath 23 resting on the inclined
surface 33.
The shape of a pusher 217 is more visible in figures 17
and 18. This pusher comprises an elongate rule-shaped
part 218 equipped at one end with a part in the shape
of a right triangle 219 through which there passes a
pin 220 which protrudes from both sides of the part
219. The vertex of the right triangle is truncated to
give a face 221 parallel to the axis of the rule-shaped
part 218.
Returning to figure 16, it can be seen that the pusher
217 can occupy two positions. In its initial position
(depicted in dotted line) it rests on the plate 215 and
faces toward the floor, so that its pin 220 is arranged
transversely with respect to the preform 5 and its face
221 is at the lower part of the inclined surface 33, in
the opening 36 in the rim 34.
When the pusher 217 is struck by the pushing finger
216, it moves, raising the inclined surface 33. In
doing this, it pushes the lath 23 which then becomes
inserted between the preform 5 and the conveyor belt 7.
The pushing finger 216 on the chain 206 lies some
distance away from the wires held by the links 207 such
that the lath 23 is introduced substantially opposite
the location on the preform 5 where said wires have
just formed the impression. The consequence of this is
that the displacement of material caused by the
introduction of the lath 23 is at least partially
compensated for by the impression. It then follows that
the preform has no lump on the opposite side to where
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the lath 23 was introduced. What this means is that
once this lath 23 has been removed, the feathering
obtained on the underside of the preform 5 does not
bear a corresponding lump on the top of the preform 5.
The pusher 217 moved by the pushing finger 216 reaches
a second position, completing its travel, in a
receptacle visible in figures 17 and 18 and which is
formed by two arched pieces 222 fixed by their upper
ends on each side of the outer end 225 of the rod 223
of a ram 224. Each side of the pin 220 of the pusher
217 is housed in an arched piece 222 and the parts 219
and 218 of the pusher 217 can fit into the space formed
between the arched pieces 222, under the rod 223 of the
ram 224.
In figures 17 and 18, the rod 223 of the ram 224 is
deployed, to receive the pusher 217.
However, as visible in figure 16, by retracting the rod
223 of the ram 224 into the body of this ram, the
pusher 217 is returned over its initial position, then,
by once again deploying the rod 223 of the ram 224, the
pusher 217 is separated from the arched pieces 222 and
drops down onto the plate 215. It therefore finds
itself in its initial position, with its face 221
inside the opening 36.
It goes without saying that the dimensions of the
pusher 217 are chosen so that it remains above the
inclined surface 33.
The ram 224 may be fixed to the frame 205 of the
apparatus, its location and size being determined
according to the pusher 217 with which it has to
collaborate. The ram 224 therefore has the function of
returning the pusher 217 to its initial position. Its
rod 223 is normally in the deployed position, waiting
to receive the pusher 217.
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Of course, the entire apparatus is designed
symmetrically, each of the chains being equipped with a
pushing finger 216 each collaborating with a ram 224,
all this being in synchronism.
The electronic and pneumatic (or possibly hydraulic)
means on the production line drive the operation of the
apparatus for making the impressions and of the device
for introducing the laths under the preform (consisting
of the means 20 to 22 and 24 to 39 described
hereinabove) so that once the pusher 217 has been
returned to its initial position and the rod 223 of the
ram 224 has been deployed once again, another lath 23
can be slipped along the inclined plane 33.
Provision may be made for actuation of the ram 224 to
be determined by detection, for example, by means of a
photoelectric sensor, of the passage of a stud or
finger fixed at an appropriate point on the chain 206,
for example in the same way as the pushing finger 216,
this stud acting as a flag, that is to say that when
detected by the photoelectric sensor positioned at a
suitable point on the production line or on the
apparatus, the electronic means command the return of
the rod 223 of the ram 224 into the body of the ram,
this return, as explained hereinabove, causing the
pusher 217 to return to its initial position.
End-of-travel sensors for the ram 224 may then, once
the rod 223 has been retracted, cause further actuation
of the ram 224 to deploy its rod 223, causing the
pusher 217 to drop into its initial position.
The frame 205 of the apparatus may, as is apparent from
figure 16, be secured to the plates 214 and 215. It
then follows that the apparatus can be used in place of
a forming plate or master roll conventionally used.
