Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates to a method
for the manufacture of products from moulding compounds
in dry or viscous liquid form such as concrete or
plastics to which a filler, preferably of wood material,
has been added to a high degree. In such a method a ;
thermosetting plastics material or otherwise solidifiable
material such as concrete is aggregated with the finely
divided filler so that a moulding compound is obtained,
which is introduced into a mould in which it is subjected
to pressure in order to shape the desired product.
The invention also relates to an apparatus
provided to carry out the above mentioned method. ?
Plastics have turned out somewhat unfavourable
for the production of thickwalled objects, such as parts -
used in the building industry such as window sashes,
window wings, doors, door ~ashes, and other parts used
in interior decoration. This is because of the high
volume price of plastics in relation to the prices of
conventional materials like wood and wood particle board.
For manufacture of the parts mentioned above it would s
of course be desirable to take advantage of the good
qualities o plastics, i.e. easy maintenance, attractive
appearance and ease of moulding, so that moulding methods
would replace the previously used, usually expensive,
- manufacturing methods involving cutting operations.
One solution is to let plastics constitute
only a minor part of the products, as is done in the
manufacture of wood particle board, thus making the
products go further by adding fillers like sawdust, ;
waste from chopping operations, cutting shavings, coarse
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wood pulp, or similar fillers. ~owever, a raw material -
; containing a sufficiently large portion of fillers in
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order to yield a product of sufficiently low price has
shown such poor mo~llding qualities that the conventional
injection moulding processes for plastics cannot be used.
It is an object of the invention to make it
possible to use a mixture of plastics or other solidifiable
material and filler, in which at least in suitable case~
the proportion of filler can be greater than is normally
possible in connection with known injection moulding -
methods. By such an arrangement it may be that the
proportion of plastics or other solidifiable material
entering into the mixutre can entirely be determined
on the basis of the re~uired strength without having to
consider the requirements to enable the moulding compound
to be used in a conventional processing method.
According to one aspect of the present invention,
a method is provided for the manufacture of a product from
a filled solidifiable moulding compound in dry or viscous
liquid form, comprising the step of introducing a moulding
compound to a mould composed of a bottom and side wall
means defining a mold cavity having an opening giving direct
access to the interior thereof, thereafter inserting a ram
in said opening to subject the moùlding compound to a
generally non-elastic pressure in the mould cavity, and
subjecting both the moul-d and the ram to blows producing
vibrations--predominantly transverse with respect to the
direction of the ram pressure, said blows being generated
by a plurality of sources synchronised such that the blows
to which the mould is subjected are oriented in a direction
generally opposite to the direction of the blows to which
the ram is subjected.
In another aspect of the present invention, an
apparatus is provided for manufacturing of a product from
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a filled solidifiable moulding compound in dry or viscous
liquid form, comprising an open mould composed of a bottom
: portion and side wall means, and a ram for inserting into the
mould to enclose the moulding compound therein, a working
table provided to carry the mould and opposite thereto a
pressing had adapted to ~e driven ~mder a generally non-elastic
pressure towards the table to force the ram into the mould,
the table and the pressing head both including vibrators
provided to generate blows producing vibrations predominantly
transverse with respect to the direction of the ram pressure,
said blows being generated by a plurality of the vibrators
synchronised so that the vibrators of he table are arranged
to produce blows in a direction generally opposite to the direc-
tion of the blows generated by the vibrators of the pressing
head.
The invention as recited in the afor~said
general terms provides the utility of an improved distribution
of particles within the moulded compound even when the particles
are comprised of different shapes and different specific weight
fractions.
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The accompanying drawings illustrate the ~ ¦
invention and show various embodiments of apparatus in
accordance with the present invention.
In the drawings:- ¦
Fig. 1 shows a press in side elevation;
Fig. 2 is a vertical cross-sectional view along 1
line II-II of Fig. l; ,
Fig. 3 is a vertical cross-sectional view along
line III-III of Fig. l; ¦~
Fig. 4 is a vertical cross-sectional view of
~ a vibrator for the press of Fig. 1;
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Fig. 5 i s a side elevation of the vibrator of
Fig, 4;
Fig. 6 is a part sectional view of a mould;
Fig. 7 is a graph illustrating the superimposition
of vibrations of different frequencies;
Fig. 8 is a broken perspective view illustrating
the moulding of a loading pallet;
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Fig. 9 is a cross-sectional view on the line IX of
Fig. 10 of a mould for manufacturing an alternative loading pallet;
Fig. 10 is a cross-section on the line X of Fig. 10;
Fig. 11 is a side view of a panel for roof covering;
Fig. 12 is a cross section on the line XII of Fig. 11;
and
Fig. 13 is a cross-sectional view of a shoe sole
in a mould therefor.
According to Fig. 1 the press comprises frame with
`10 a support 22, a working table 23 and four pillars 24, connected
directly to the support 22 and not to the table 23, carrying
an upper part 25. The upper part 25 includes a heavy hydraulic
jack 26 with a piston carrying a pressing head 27. The working
table 23 as well as the pressing head 27 are connected to the
support 22 and the piston of the jacket 26 by means of elastic
blocks. Attached to the working table 23 and to the pressing head
27 are vibrators 28 and 29 respectively. As will be described
in the following the working table 23 is intended to carry a
mould 16 in the opening 20 of which a ram 21 is inserted. The
ram 21 is intended to cooperate with the pressing head 27 which
~ lowers the ram by means of the hydraulic jack 26.
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The pressing head 27 with the vibrators 29 is shown
from above in Fig. 2 in a section along the line II-II of Fig. 1.
The working table 23 is shown in Fig. 3 in a section along line
III-III in Fig. 1. The positions of the vibrators 28 at the under
side of the table 23 are shown. The mould 16 without the ram 21
inserted is shown in Fig. 3 placed on the table 23. As is
~' evident from Figs. 2 and 3, the table 23 and the pressing head
27 each are provided with four vibrators 28 and 29 respectively,
two of the vibrators having their axes parallel and the other two
having their axes parallel and at right angles to the first two
vibrators.
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A side elevation of a vibrator is shown in Fig. 4.
According to this figure the vibrator include~ a casing 30 with
a mounting plate 31. The casing 30 encloses an electrical motor,
the shaft 32 of which is provided at its ends with eccentric
weights 33. The weights 33 are covered by means of the hoods 34.
At each end of the shaft 32 there are two weights 33 provided
which are turnable relative to each other. However, when turning
the weights of one pair, the other pair are adjusted likewise
so that the pairs are positioned in the same way at both ends of
the shaft 32.
The vibrator is shown from the end in Fig. 5 (the hood
34 removed). As will be understood from this figure, the
vibrator and the body to which the vibrator is attached will be
subjected to a rotating force produced by unbalanced weight 33
thus resulting in frequent blows directed to the article to which
the vibrator is attached. The unbalance of the pair of weights
at each end of the shaft 32, and consequently said force, is
adjustable by turning the weights of each pair relatively to each
other. The maximum unbalance is obtained in the position
shown in Figs. 4 and 5 with the weights aligned, while, if the
~eights of each pair are turned to a position opposite to each
other, the unbalance is neutralized.
The forces produced by the rotating weights are directed
in the way indicated by the arrows in Fig. S i.e. to the right
in the quadrants I and II, to the left in the quadrants III and IV,
upwards in the quadrants IV and I, and downwards in the quadrants
II and III. If the vibrator is attached to the working table
carrying a mould containing said moulding compound the upwards
force in the quadrants I and IV results in a packing of the
moulding compound and the downward forces in the quadrants II
and III will result in a loosening of the mixture. Due
!to the inertia of the moulding compound it will be mostly packed
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when the weight passes the ~uadrants I, II. In these quadrants
said forces work to move the mould to the right and according
to the inertia of the moulding compound it will be pressed against
the inner surfaces of the mould pointing to the right, i.e. the
mixture will be pressed against the left walls of the mould.
In this way, it is possible to direct the packing of
the mixture in the desired way by means of the arrangement of the
vibrators. The arrows on Figs. 2 and 3 indicate the direction
of the forces acting on the particles and caused by the vibrations
from the combined action of the vibrators. The arrangement of
the vibrators 29 of the pressing head 27 is so chosen that the
packing effect is reversed compared to the same of the working
table. ;;
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By means of the described method it is consequently ¦
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possible to obtain a packing of the mixture along walls of a ¦
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mould of any conformation. This effect is very important; by ¦ ;~
a pressing operation, i.e. by pressing the ram down into the filled --~
mould, the pressure in the moulding compound is directed sub-
stantially in the pressing direction of the ram and because of
; 2~ the high friction between the particles of the moulding compound
the pressing pressure will not produce sufficient pressure of
the moulding compound against the side walls of the mould to j
produce the desired strength and smooth surface finish of the ~;
, parts of the workpiece which are adjacent to the surfaces formed
by said mould side walls. However, by means of the above described
vibrating method it is possible to obtain a substantially equal
~ strength and surface finish for articles, including those of
-i very complicated shape, from moulding compounds containing large
amounts of filler.
However, it is possible to further i~prove the results
by means of different vibration frequencies for the vibrators.
i; One practical arrangement for the vibrators of the pressing head
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is as follows:
Position A and C = 8900 blows per minute
Position B and D - 6000 blows per minute
These relatively high frequencies will be used for
vibrators for the pressing head and ram according to Fig. 2,
while for the mould according to Fig. 3 the following lower fre-
- quencies are proposed:
- Position A and C = 2900 blows per minute
Position B and D = 2600 blows per minute
Under some circumstances it is however more suitable
to change the arrangement so the lower frequencies are used for
the ram and the higher frequencies for the mould. The most
suitable arrangement depends on the nature of the moulding com-
pound. For concrete the best result will occur if the higher
;
frequencies are directed towards the mould, while for plastics
compounds with wood filling material it is more suitable to use
the higher frequencies for the ram. It is generally necessary to
determine the frequencies to be used by means of practical
i~' experiments, and the arrangement to be used thus depends on the
nature of the moulding compound as well as the design of the
mould.
In order to reach the most suitable arrangement the
! vibrators consequently have to be adjustable according to
frequency and their position relative to the mould. Vibrators
intended to work at the same frequency have not necessarily to
;i be synchronized in any mechanical or electrical way. In practice
1 it is shown that if the vibrators are adjusted to work at about
.~ the same frequency they will be self-synchronizing by means of
;~ the blows transformed by the base. In the drawings the
, 30 vibrators are placed intermediate of the side walls of the
; mould when viewed from above but positioning at the corners of
the mould base is also possible.
Fig. 7 illustrates the use of different frequencies
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at the same time and the resulting influence on the effect ofthe blows ~the amplitude). Fig. 7 shows the superimposition of
two sine curves with dîfferent frequencies. The addition will,
as shown, result, in a periodical increasing of the amplitude in
that moment when the blows are directed in the same way. By
practical experiment it can be shown that this periodical change
of the effect of the blows will result in an exceptional flow-
ability and packing of the compound. In practice the described
method is very advantageous and by means of the same it has been
possible to manufacture work pieces with considerable variation
in thickness in the material and yet, in spite of this, with
practically the same density in the different parts. When
work pieces are manufactured by conventional methods, not using ~;
the method according to the present invention, the density in the
different parts will be very different and in thick parts cavities
also will occur.
The advantages obtainable using the present invention
are mainly the result of an intensive experimental work during a
long period of time, which work is based on certain theories and
feed-back of the experimental results. The theory relating to
the use of vibrations of different direction and optionally
different frequency, to subject the ram and mould to blows is
founded on the assumption that particles with different mass
are influenced in different ways by different frequencies and it
is assumed that the same is true with regard to different
amounts of moulding compound enclosed in cavities of the mould
with different volume.
The following description is an example of how the
method according to the invention can be carried out:
1. The mould is filled to the intended depth with
compound. The mould is suitably vibrated during filling which
will shorten the necessary time. Alternatively, the vibration can
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be made after filling and it is usually necessary to continue
the vibration even after the intended amount of compound is
filled in the mould. From experiment it is shown that the
application of vibrations with the moulding compound not under any
pressure in the moula and not enclosed between the mould parts
will give an inclined upper surface of the moulding compound as
shown in Fig. 1 (line a in the mould part 16).
2. The ram is lowered towards the free surface of the
compound in a relatively slow cycle (of the order of tens of
seconds). By means of the vibrations and the pressure from
the ram the moulding compound is equally distributed in the mould.
During the pressing of the ram against the moulding compound
the definite distribution of the compound in the mould is effected
and the compound will be packed together so that all of the
trapped air will be removed.
3. After a period of vibrating under relatively low
pressure, the mould is subjected to the high pressure necessary to
form the product (a pressure in the range of thousands of N
(Newton) depending on the size of the mould) and the ultimate
compression of the moulding compound will occur.
; 4. Now the entire mould with the ram remaining in
the mould will be removed from the press and tra~sported to a
' place in which the product will be hardened (cured). For
plastics mould compounds the curing will be done by heating in a
heat chamber (oven).
The following description illustrates the filling
of the mould and the manufacture of products of,different shapes.
In Fig. 6 a portion of a mould 16 is shown. As
indicated, the mould contains moulding compounds of unequal
density; adjacent to the vertical wall of the mould is a compound
35 with high density and against the middle of the mould is a ¦~
compound 36 with lowex density. For the distribution of the
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lV~t:iOl~
compound 35 a board 37 with suitable openings 38 is provided.
After the compound 35 has been filled along the walls of the
mould through the openings 38 in the way described later, the
board 37 is removed and the compound 36 is filled through the
uncovered opening 20 of the mould. By packing the compound in
the described way and vibrating the compound 35 with the higher
density it will be tighter packed. By this method it is possible
to increase the strength of the border parts of the produced
article and cause them to become sufficiently packed even if the
walls of the moulds extend in the pressing direction of the
ram and even if undercuts are present.
In Fig. 8 a mould for a pallet 97 is shown (the pallet
is shown upside down in the mould). The pallet, which is made
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in one piece, comprises three supporting beams 98 and at right
angles thereto parts 99 forming the upper surface and having four
openings 100. The mould has a bottom 101 and hinged thereto
four lockable sides 102. To the opening 100 correspond four bodies
103 (only two are shown) extending from the bottom 101. The
parts 99 are formed by means of six ram pieces 104 (only two are
shown) connected to each other by means of rods 105. For the
pressing of the beams 98 three ram pieces 106 (only one is shown)
are provided. The rampieces 106 are connected by means of beams
107, provided to press on the rampieces 104 when the ram formed
by the rampieces 106 and the beams 107 is pressed down by means
; of the pressing head.
In Figs. 9 and 10, a mould for another type of
pallet is shown. The pallet 115 is similar to the pallet 97
in Fig. 8 and comprises three beams 116 connected by means of a
bottom portion 117. However, contrary to the pallet in Fig. 8
the beams 116 are hollow. In each of the outer beams there are
three conical blind holes 118 and in the middle beam there are
three larger conical blind holes 119. Between said holes
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openings 120 extend through the beams. The holes 118 and 119
are formed by corresponding parts 121 and 122 of a part 123 of
the pressing head 124. The surfaces, in the moulding position
directed upwards, surrounding said holes 118, 119 are formed
by surfaces 131 of said part 123 of the pressing head. The
openings 120 are formed by means of slides or retractable cores
126 which are slidable in the wall 127 of the underpart 128 of
the mould from an upper position shown to the left in Fi~. 9
to a lower position shown to the right in Fig. 9. The guide in
the wall 127 for the sliding movement of the slide 126 is pro-
vided with sealing elements so that compound will not be let out
through the guide by sliding of the slide 126. The slide or
core 126 can be retracted out from the mould by means of ring
shaped holders 129.
The surfaces of the beams positioned between the
surfaces surrounding the holes 118, 119 are formed by means of
, . .
surfaces 130 in further parts 131 of the pressing head 124. ;~
The parts 131 are placed in recesses 132 in the part 123 and will
be moved by means of the same by the pressing operation.
The main part of the bottom portion 117 between
the beams 116 will be formed by means of the slide 126 when the
same is moved towards its lower position. The slides 126 will
be moved by means of further parts 133 of the pressing head 124.
~ The part 133 is provided with recesses 134 in which the slide 126
- is positioned when, by lowering the pressing head 124, the
, part 133 is moved by means of the part 123. The part 133 further
shows surfaces 135 intended to form the remaining part of the
bottom portion 117 between the beams 116.
The surface of the bottom portion 117 directed down-
wards in the moulding position is formed by means of a bottom
plate 136 of the under part of the mould. This plate is movable
by means of ejecting bars 137 for the removal of the finished
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pallet out of the mould.
When filling the mould shown in Figs. 9, 10 the parts
of the pressing head as well as the slides 1~6, are placed at
suitable levels so that the depth of the moulding compound will
be ~uited to the different thickness of the finished product. By
pressing the part 123, the pressing head 124 is lowered and will
bring the parts 131 and 133 along. At the same time~he part 133
will press the slides 126 downwards to the position shown to the
right in Fig. 9 and in Fig. 10. Thereby the moulding compound
will be pressed between the different parts of the pressing head
124 and the bottom plate 136 of the under part 128 of the mould
respectively between the under surface of the slides 126 and
said bottom plate. The finished product can be ejected resting
on the bottom plate 136 by means of the ejecting bars 137.
Fig. 11 shows an example of a product which can be
produced by the method according to the invention in the form of
a roof panel. The panel is intended to be laid directly on the
roof beams and the panels are intended to be joined together
by means of sealing joints 108. The panel is provided with ledges
109 intended to work as carrying elements for pan tiles. In order
to make it possible for rain water un~er the tiles to flow down-
wards the ledges are provided with notches 110 (Fig. 12).
In Fig. 13 a mould 111 with a pressing head 112 is
shown. The mould, which preferably is made as a multiple com-
partment mould, is provided for the manufacturing of bottoms
113 of moulding compound for wooden shoes. As is evident from
the figure, the cavity for the shoe bottom 113 is laid at an .
oblique angle in relation to the resting surface 114 of the
mould. By means of vibrations according to the
method of the invention it is possible to direct a flow of mould-
ing compound and exert a packing effect towards the heel of the
shoe bottom 113, which will increase the strength of the heel.
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It is not possible to obtain sufficient strength in the heel
in the pressing operation merely by means of the ram 112; the
strength in a simple pressing operation or said moulding compound
will depend merely upon the thickness in the pressing direction.
However, by means of the present method it is possible to obtain
a precompression of the mixture and a packing of the same between
the mould and the ram during the pressing operation, by means of
which it is possible to obtain the desired strength in all parts
of the article.
As described in connection with Fig. 6 the mould can
be filled with moulding compounds of different compositions with
different characteristics according to the obtainable strength,
density and so on. The different compounds have, as described
before, to be distributed in a suitable way according to the
shape of the mould and the desired characteristics of the
manufactured article. In order to obtain this selective
distribution the filling will take place in several steps by
using boards (37 in Fig. 6), cooperating with the board 17,
with openings (38 in Fig. 6) provided to let the moulding compound
~ through. This first compound can then be compressed prior to
insertion of further moulding compound. In certain cases therefore
the compression can be directed to certain-parts of the mould and/
or to certain parts of the moulding compound in which the density
is higher than in the remaining parts as described before.
; The above modification using different moulding
compounds is sometimes necessary under special circumstances e.g.
for making products of very complicated shape and special demands
of strength. In general it is, however, not necessary to use
such a modification as by using the vibrating method according to ~-
30 the present invention, products of very complicated shape can
also be produced.
In the foregoing only two working stations have been
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described ~or the production of plastics or concrete products,
i.e. the mould equipped with the vibrators and the hardening
(curing) station. After the pressing operation in the mould it
; is most suitable to transport the mould to the hardening station
as mentioned before. Even if it is possible to fill the mould
- before the pressing operation, it may be more practical to per-
form the filling operation and precompression by means of
vibrating in a station upstream of the pressing operation and to
move the mould stepwise from station to station. In this case at
least the precompression station has also to be provided with
vibrators of the kind described in connection with Figs. 1-5.
By using a mould according to Figs. 9 and 10, the
slide 126 is drawn out during the filling operation. Before the
pressing, the slide 126 is now preferably displaced and pushed
into the moulding compound in its upper position, which is
facilitated by the pointed end of the slide. Thereafter the
pressing cycle takes place by moving down the ram 124~ the slide
` 126 following in the downwards direction, said slide occupying
, its intended final lower position when the compound below the
~ 20 slide has reached the intended thickness. Thus the compound
3 is compressed in the mould cavity-in an unbroken layer sidewise
of the slide by means of the head, but under the slide by means
of the slide itself, which during its downwards movement
compresses the underlying compound, while compound above the
slide can be compressed between the slide and the ram. A slide
not vertically displaceable would prevent the moulding compound
below the slide being compressed to a sufficient degree.
When producing a pallet 97 according to Fig. 8 the
side walls 102 of the mould are raised and locked together. The
bottom of the mould cavity forms a plane with the four bodies
103 projecting therefrom. The mould is now connected to the board
17 and the moulding compound filled in a layer suitable to form
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the parts 99. Thereafter the six ram pieces 104 are inserted in
the mould and a new layer of moulding compound, suitable to
form the beams 98 is filled in the mould in the areas left behind
the bodies 103 and the ram pieces 104. sefore the pressing
operation the ram 106, 107 is inserted in the mould. By pressing
down the same it will press down the ram pieces 1~4 by means of
the parts 107. By adjusting the distance between the underside
of the ram pieces 106 and the underside of the parts 107~ to the
height of the ram pieces 104 it is possible to obtain a suitable
compression of the different parts of the pallet g7.
When manufacturing the roof panel of Figs. 11 and 12
it is important to reach a high strength in the ledges 109,
which is difficult because of the larger thickness o~ the same
compared with the thickness in the remaining part of the panel.
However, by means of the vibrating method according to the
present invention it is possible to produce a packing effect
sidewards in relation to the pressing direction, which is to
the left and to the right in Fig. 11 as viewed with the panel
horizontal, i.e. in the direction parallel to the main extension
of the panel. Thereby it is possible to obtain a higher pressure
in the ledges 109 than is obtainable by means only of the ram
pressure. The suitable direction of the packing effect
produced by the vibrators of the mould is indicated by means of
~ an arrow to the right in Fig. 11 as viewed with the panel hori-
; zontal whereby the direction of the packing effect from the ram
is reverse, according to the arrow to the left.
In conventional methods it has been necessary to
ease the pressure one or several times during such a setting
process in order to let the steam escape, which has resulted
1 30 in rather large rough portions on the surfaces of the products,
which portions have had to be removed in a finishing operation.
The positions of the vibrators 28, 29 may be changed,
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as illustrated with an X (see Figs. 2 and 3) indicated at 28l
and 291 respectively, and with the net sequence of vibrations
directed according to the arrows shown.
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