Note: Descriptions are shown in the official language in which they were submitted.
~5~
CLAMPING ARRANGEMENT FOR LUMBER ELEMENTS
BACKGROUND OF THE INVENTION
The present invention relates to the clamping of
workpieces in general, and more paxticularly to an arrangement
for clamping (maintaining firmly in position) lumber elements,
such as tree trunks, lumber beams or the like, during the pro-
cessing thereof, especially those which are integrated into a
sawing installation.
Currently, relatively large tree trunks, lumber
beams or the like which are to be subdivided in a sawing in-
stallation into boards, planks, small beams or the like are
held in position by clamping wedges which act on the lumber
element from above and from below.
This conventional approach brings about the dis-
advantage that the clamping wedges penetrate, dig into or
otherwise deform the lumber element to be processed and thus
damage the surface region of the lumber element. Inasmuch as
the tree trunk being processed is turned after each sawing or
cutting operation about its longitudinal axes by a quarter of
its circumference, the above-mentioned penetration of the
lX735'.~9
clamping wedges into the lumber element, and thus the atten-
dant damaging of the boards or the like cut from the lumber
element, occurs time and time again during each clamping opera-
tion following such turning.
A further disadvantage of the use of the clamp-
ing wedges reside~ in the relatively low utilization of or
yield from the cross section of the lumber element, inasmuch
as the cross section of the lumber element can be sawed only
to an extent permitted by the clamping wedges, that is until
the path of movement of the saw relative to the lumber element
during the sawing operation reaches the clamping wedges. After
that, what remains of the original lumber element is basically
waste or refuse wood. Yet, especially nowadays, with the rel-
atively high lumber prices, it is desired to utilize the valu-
able lumber material to the utmost possible extent.
SUMMARY OF THE INVENTION
Accordingly, it is a general object of the pres-
ent invention to avoid the disadvantages of the prior art.
More particularly, it is an object of the pres-
ent invention to provide a clamping arrangement for lumber
elements which does not possess the drawbacks of the known
arrangements of this type.
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1~735~9
Still another object of the present invention is
to devise an arrangement of the type here under consideration
which would render it possible to clamp the lumber elements in
such a manner as not to damage the surface areas thereof.
It is yet another object of the present inven-
tion to design the above arrangement in such a manner as to
render it possible to utilize the entire cross section of the
lumber elemènt, without leaving any unutili2able remainder.
A concomitant object of the present invention is
so to construct the arrangement of the above type as to be
relatively simple in con~truction, inexpensive to manufacture,
easy to use, capable of automation, and yet reliable in
operation.
In keeping with these objects and others which
will become apparent hereafter, one feature of the present
invention resides in an arrangement for clamping a lumber
element during its processing, especially in a sawing instal-
lation, this arrangement comprising at least two spaced abut-
ment members having abutment surfaces for the lumber element
and a substantially vertically extending suction plate situ-
ated between the abutment elements and including an upright
contact plane. The suction plate is movable transversely to
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the contact plane thereof and has a plurality of suction open-
ings capable of exerting suction effects on the lumber element
which is juxtaposed with the contact plane. This arrangement
further includes sensing means including a plurality of con-
tactless sensors for sensing the presence of the lumber ele-
ment at the respective suction openings and for generating
corresponding indication signals, and means for controlling
the suction effect of the suction openings in dependence on
the indication signals.
Advantageously, the suction openings of the suc-
tion plate are arranged at the contact plane in a plurality of
substantially horizontally extending, vertically spaced paral-
lel rows each including at least two of the suction openings,
and one of the sensors is then associated with each of the
rows. The sensors may be constituted by light barriers, by
photoelectric cells, or by laser light eyes. It is further
advantageous when the suction plate has a rectangular basic
configuration, with the longer dimension of the rectangular
basic configuration extending in the horizontal direction and
in the longitudinal direction of the lumber element, when the
suction openings of the rows are arranged in respective vertic-
ally extending columns above one another at predetermined dis-
tances from each other, and wherein the two suction openings
of each of the rows are spaced from each other in the longitu-
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dinal direction by a distance which is a multiple of the prede-
termined distance.
According to a further advantageous aspect of
the present invention, the sensors are arranged on the suction
plate in a vertically extending column which is laterally ad-
jacent to one of the columns of the suction openings. In this
context, it is advantageous when that one of the sensors which
is associated with a lowermost one of the rows of suction open-
ings is situated at the elevation of the lowermost row, whilethose of the sensors which are associated with the respective
higher ones of the rows of the suction elements are upwardly
offset by one row relative to the associated one of the rows.
The suction plate is advantageously provided at the contact
plane thereof with a circumferential seal arranged at a margin-
al region of the suction plate, and with a plurality of addi-
tional seals each extending between two vertically adjacent
ones of the rows of the suction openings.
It is particularly advantageous when the control-
ling me~ns includes a plurality of valves which control the
supply of underpressure to the suction openings, an electrical
switching and control device operative for generating control
signal for controlling the opening and closing of the valves,
and conduit means for connecting the sensors with the elec-
1~7354~
trical switching and control device for supplying the indica-
tion signals thereto, and for supplying the control signals to
the valves.
It is also advantageous when there are further
provided means for mounting the suction plate, such mounting
means including a carrier frame movable on respective guides
in a hori20ntal direction transversely to the contact plane,
and a centrally disposed pivoted suspension which mounts the
suction plate on the carrier frame. Then, there may be further
provided a vacuum accumulator and a vacuum distributor which
are mounted on the cArrier frame, a vacuum pump, and an air
conduit connecting the vacuum pump with the vacuum accumula-
tor. The arrangement may further advantageously comprise two
additional air conduits connecting the vacuum accumulator with
the vacuum distributor, and two valves each interposed in one
of the additional air conduits. The additional air conduits
may advantageously open into the vacuum distributor laterally
at respective oppositely situated sides of the vacuum distri-
butor.
When, as mentioned before, the suction openingsare arranged in respective horizontally extending rows which
are arranged at vertical spacings from one another, there is
advantageously further provided a plurality of distributing
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air conduits each connecting the vacuum distributor with one
of the suction openings and a plurality of valves each inter-
posed in one of the distributing air conduits except for those
which lead to the suction openings of the lowermost one of the
rows.
According to another advantageous facet of the
present invention, there is further provided an additional
plate arranged at a rear side of the suction plate and includ-
ing a plurality of heating elements.
It may be seen from the above that the clampingarrangement according to the present invention operates with
an upright vacuum suction plate which pulls the lumber element
to be processed especially sawed, firmly against two abutments
and thus assures, on the one hand, a clamping action which is
protective of the surface region of the lumber element, that
is, it does not inflict any damage to such surface region and,
on the other hand, renders it possible to saw the entire cross
section of the lumber material into useful products, without
leaving any unutilizable waste pieces. The suction plate is
subdivided into individual suction zones which are controlled
by respective sensors which cooperate with the lumber element
to be processed and which exactly detect or register the cross
section of the lumber element as it grows smaller and smaller
iZ~ 51~
as the sawing operation progresses and correspondingly switch
the respective suction zones on and off.
Furthermore, the suction plate is movable with
respect to the abutm~nts, in order to avoid damage to the suc-
tion side of the suction plate, so that the suction plate is
moved toward the lumber element and attracts the same by suc-
tion only after the lumber element has already been brought in-
to abutment with the aforementioned abutments. Inasmuch as the
lumber element is constantly or frequently turned about its
longitudinal axis during the subdivision of its cross section,
the sensors sense or detect the size of the cross section
after each turning and the corresponding suction zones are
then controlled.
The vacuum suction plate of the present inven-
tion has a simple construction and operates with a high degree
of reliability. Moreover, it is also possible to easily incor-
porate or integrate the clamping arrangement of the present
invention into a sawing installation.
BRIEF DESCRIPTION OF THB DRAWING
The present invention will be described below in
more detail with reference to the accompanying drawing in
which:
5~
Fig. 1 is a perspective view of a clamping ar-
rangement according to the present invention for clamping
lumber elements, wherein the arrangement is shown to include
an upright vacuum suction plate positioned between two abut-
ment members for the lumber element and to be integrated into
a sawing installation;
Fig. 2 is a side elevational view of the clamp-
ing arrangement of Fig. 1, showing a vacuum accumulator, vacu-
um distributor, air filter and suction plate suspension;
Fig. 3 is a top plan view of the clamping ar-
rangement of Fig. 2;
Fig. 4 is a front elevational view of the suc-
tion plate of the clamping arrangement of Fig. 1 depicting
respective suction openings and sensors associated therewith
Fig. 5 is a somewhat diagrammatic view illustrat-
ing the components of the clamping arrangement of Fig 1 andinterconnections between such components;
Fig. 6 is a diagrammatic simplified top plan
view of the abutments and the suction plate of the arrangement
of Fig. 1, with the suction plate being in its retracted
1~7~5~
position while the lumber element is being delivered to the
abutments; and
Fiq. 7 is a view similar to Fig. 6 but with the
suction plate in its extended or operative position in which
it clamps the lumber element against the abutments.
DETAILED DESCRIPTION OF THE P~EFERRED EMBODIMENT
Referring now to the drawing in detail, and
first to Fig. 1 thereof, it may be seen that the reference
numeral 1 has been used therein to identify a lumber element,
such as a tree trunk, a wooden beam or the like, which is to
be clamped (firmly held in position) during its processing,
especially during sawing, by a clamping arrangement according
to the present invention. The clamping arrangement includes an
upright vacuum suction plate 2 which is movable with respect
to contact surfaces ~abutments) 3 for the lumber element 1
transversely to its vertical upright plane and is provided
with a plurality of suction openings 4 to 8. The suction
openings 4 to 8 are controlled as to their suction effect,
that is, switched or and off so that they either exercise or
do not exercise the suction effect, by means of respective
sensors 9 to 13 which sense the lumber element l in a con-
tactless manner.
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It is currently preferred for the suction plate
2 to have a rectangular basic configuration and to be so ori-
ented that the longer side of its rectangular configuration
(longitudinal direction) extends in the longitudinal direction
of the lumber material 1, that is, in the horizontal direc-
tion.
As may be seen particularly in Fig. 4 of the
drawing, the suction openings 4 to 8 of the suction plate 2
are arranged in several parallel rows tsuction zones) A to E
which are situated one above the other. Each of the rows A to
E includes at least two of the suction openings 4 to 8, the
two openings 4 to 8 provided in each of the rows A to E being
disposed at a relatively large distance from one another,
while the suction openings 4 to 8 which are arranged above one
another in the respective rows A to E and which are disposed
in respective vertical columns or rows are spaced by a rel-
atively small distance from each other. The two suction open-
ings 4 to 8 arranged in the respective one of the rows A to E
extending in the longitudinal direction of the suction plate 2
are spaced from each other by a distance which is a multiple
of the distance separating the vertically adjacent ones of the
suction openings 4 to 8 from each other.
12'~3549
A different one of the sensors 9 to 13, which
may be constituted by light barrier devices, photoelectric
cells, laser-light eyes or the like, is associated with each
of the suction opening rows A to E. ~s also shown in Fiy. 4 of
the drawing, the sensors 9 to 13 are also arranged vertically
above one another and laterally of one of the vertically ex
tending suction openin~ columns or rows.
At the suction side, the suction plate 2 is pro-
vided at its marginal portion with a circumferential seal 14.Furthermore, an additional seal 15, which also extends in the
longitudinal direction of the suction plate 2, is arranged be-
tween each two of the horizontally extending suction opening
rows A to E, so that each of the suction zones A to E is separ-
ated from (closed with respect to) the other suction zones A
to E.
The suction plate 2 is supported by means of a
central articulated suspension 16 on a carrier frame 17. The
carrier frame 17, and thus in the final analysis also the suc-
tion plate 2, is movable in a manner of a carriage or slide on
horizontal guides 18 in opposite directions transversely of
the vertical upright plane of the suction plate 2, and thus
also transversely with respect to the longitudinal direction
of the lumber element 1 (steplessly or infinitely shiftable in
1;~73S~
the directions indicated by arrows F and G in Fig. 2 of the
drawing).
The suction plate 2 is situated in its upright
position between two upright abutments 3 which constitute the
bearing surfaces for the lumber element 1 to be processed and
which are parts of a sawing device 36, into which the clamping
arrangement of the present invention is integrated.
A vacuum accumulator 19 and a vacuum distributor
20, which are constituted by closed containers, chambers, hous-
ings or the like, are arranged on or at the carrier frame 17.
As shown particularly in Fig. 5 of the drawing, the vacuum ac-
cumulator 19 is in communication, via two air conduits 21 each
of which has a valve 22 incorporated therein, with the vacuum
distributor 20. In the illustrated construction, the two air
c~nduits 21 open laterally into the vacuum distributor 20 from
two mutually oppositely situated sides of the vacuum distribu-
tor 20. An underpressure is created in the he vacuum accumula-
tor 19 through an air conduit 23 by a vacuum pump 25, the air
conduit 23 having a venting valve incorporated therein.
An air conduit 26 extends from the vacuum distri-
butor 20 to each of the suction openings 4 to 8. As shown in
Fig. 5, those of the air conduits 26 which lead to the suction
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openings 5 to 8 have respective valves 27 incorporated there-
in, while the two air conduits 26 which lead to the two lower-
most suction openings 4 do not have any valves 27 included
therein. Figs. 2 and 6 indicate that the air conduits 26 have
respective air filters 28 incorporated therein.
As indicated in Fig. 3 of the drawing, the sen-
sors 9 to 13 are connected by electrical conduits 29 with an
electrical and electronic switching and control arrangement
3~. The switching and control arrangement 30 is operative for
controlling the valves 27 and 22 and, as the case may be, even
the vacuum pump 25.
Having so described the construction of the ar-
rangement of the present invention, the operation of this ar-
rangement for clamping the lumber element 1 by means of the
suction plate 2 and the abutments 3 will now be explained in
some detail, still with reference to the drawing.
The lumber element 1, such as a tree trunk or a
beam, is delivered to the abutments 3 transversely to its lon-
gitudinal direction, as indicated by an arrow H in Fig. 6, on
guides 31 by suitable delivery equipment, such as chains pro-
vided with entraining members, shovels or the like. At this
time, the suction plate 2 is retracted with respect to the
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12~735~9
abutments 3 in the direction of the arrow F, so that the lum-
ber element 1 which reaches the abutments 3 with a relatively
high amount of kinetic energy and which thus exerts a relat-
ively high amount of pressing force on the abutments 3 cannot
damage the suction plate 2.
After the lumber element 1 has reached its posi-
tion in which it i5 in contact with the abutments 3, the suc-
tion plate 2 is displaced, as indicated in Fig. 7 of the draw-
ing, in the direction of the arrow G toward the lumber element1 and attracts the lumber element 1 in the direction of an
arrow K by exerting a suction effect thereon, thereby pressing
the lumber element 1 firmly against the abutments 3, so that
the lumber element 1 is drawn to the suction plate 2 by the
vacuum applied thereto by the suction plate 2 and is held
firmly in a clamped condition thereof on the abutments 3 by
the action of the suction plate 2.
At this time, the processing of the lumber ele-
ment 1 by a saw 32, which is also indicated in Fig. 7 of thedrawing and which moves, for instance, in and opposite to the
longitudinal direction oE the lumber element 1, can proceed
and the lumber element l is thus subdivided into smaller
boards, planks, beams or the like.
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1273~
As soon as the lumber element 1 comes into abut-
ment with the suction plate 2, those of the sensors 9 to 13
which are covered by the lumber element 1 detect the presence
of the lumber element 1 thereat and then control the suction
openings 4 to 8 in such a manner that, by opening the respec-
tive valves 27, an underpressure is applied by the vacuum dis-
tributor 30, that is, air pressure is aspirated into the suc-
tion openings 4 to 8, and consequently, the vacuum zones A to
E have vacuum created therein. Fig. 7 shows that the lumber
element 1 is held firmly in position by the thus applied vacu-
um until the sawing operation has been completed. Then, the
switching and control arrangement 30 closes the valves 27
which control the creation of a vacuum to the suction openings
5 to 8, so that the application of underpressure to these suc-
tion openings 5 to 8 is discontinued.
As mentioned before, no valves 27 are interposed
into the air conduits 26 leading to the two lowermost suction
openings 4, so that these suction openings 4 constantly draw
air in, so long as the lumber element 1 is present at the re-
gion of its sensor 9, regardless of whether this lumber ele-
ment 1 is situated directly at the suction plate 2 or at a dis-
tance therefrom.
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~ 7~ss~
The lumber element 1 is turned several times dur-
ing the sawing thereof into boards, planks or beams about its
longitudinal axis. This is accomplished by means of pivotable
lifting fork elements 33 of the sawing device 36.
As a result of the turning and subsequent cut-
ting of the lumber element 1, the latter becomes smaller and
smaller after each cutting operation, so that not all but only
some of the suction openings 4 to 8 remain effective, namely
in each instance those for which the associated sensors 10 to
13 still detect the presence of the lumber element 1.
The suction openings 8 are controlled, that is
switched on and off, by the sensor 13, the suction openings 7
by the sensor 12, the suction openings 6 by the sensor 11, and
the suction openings 5 by the sensor 10. Inasmuch as the
height of the lumber element 1 gradually decreases as the
cross section of the lumber element 1 is being reduced, since
the lumber element 1 is always supported on the guides 31
which thus serve as a reference surface or plane, the suction
openings 8 to 5 are being switched off from above to below. On
the other hand, the two lowermost suction openings 4 draw air
in constantly and are switched off only when the lumber ele-
ment 1 is not present at the suction plate 2 any longer. Thus,
it may be seen that the switching on and switching off of the
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1273~;~9
suction openings 4 to 8 is dependent on the size of the cross-
sectional area, and thus on the effective height, of the lum-
ber element 1, and that the effective height of the lumber
element 1 is detected or registered by the sensors 9 to 13 and
the operation of the suction openings 4 to 8 is controlled
accordingly.
As indicated in Fig. 3 of the drawing, the suc-
tion plate 2 may be so constructed as to be heatable, in that
an auxiliary plate 34 having heating elements 35 is mounted on
the back of the suction plate 2 and transfers the heat pro-
duced by the heating elements 35 to the suction plate 2. This
is particularly advantageous when the sawing installation is
operated during a cold time of the year, particularly in an
unheated environment, since then the freezing up of the suc-
tion openings 4 to 8 is prevented even if the lumber elements
1 being supplied to the sawing installation have moisture,
snow or ice layers or patches thereon.
As a result of the provision of the pivotable
suspension 16 for the suction plate 2, the suction plate 2 can
become fitted in an advantageous manner to the longitudinal
form of the lumber element 1, as a result of which there is
always obtained a secure contact between the suction plate 2
and the lumber element 1.
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~;~73549
It is also within the framework of the present
invention and contemplated to also utilize this clamping ar-
rangement with the vertically extending suction plate 2 for
the clamping and firm holding of other workpieces in other
branches of industry.
The suction openings 4 to 8 are configured, as
indicated in Fig. 3 of the drawing, as sink holes and the sen-
sors 9 to 13 are supported in the suction plate 2. The air
conduits 21, 23 and 26 are preferably constituted by flexible
hoses; however, metallic air conduits may be used as well, at
least partially. The vacuum pump may be also mounted on the
carrier frame 17 or arranged in the sawing installation at a
distance from the carrier frame 17.
The lumber element 1 is indicated in Fig. 2 of
the drawing in dash-dotted lines. This particular lumber ele-
ment 1 has such dimensions that it is attracted to the suction
plate 2, and thus clamped, by the vacuum or suction effect ex-
erted thereon by the suction rows A, B and C. On the otherhand, the two suction rows D and E which are situated above
the suction rows A, B and C are ineffective, as the sensors
associated therewith are not covered by the lumber element 1.
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i~'73S4~
While the present invention has been described
and illustrated herein as embodied in a specific construction
of a clamping arrangement for a sawing installation, it is not
limited to the details of this particular construction, since
various modifications and structural changes are possible and
contemplated by the present invention. Thus, the scope of the
present invention will he determined exclusively by the
appended claims.
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