Note: Descriptions are shown in the official language in which they were submitted.
CA 02247136 1998-08-21
WO 97130830 PCTISE97l00234
A METHOD AND AN APPARATUS FOR TURNING BOARDS
TECHNICAL FIELD
The present invention relates to a method of turning boards which are
transported with their longitudinal direction transverse to the direction of
movement of a conveyor with uniformly spaced conveyor dogs, the boards
being at least partly driven by the front sides of the dogs in abutment
against
the rear edges of the boards.
The present invention also relates to an apparatus for turning boards and
comprises a first conveyor with uniformly spaced conveyor dogs for
transport of the boards with their longitudinal direction transverse to the
direction of movement of the conveyor.
BACKGROUND ART
In the refining of timber in the form of boards in sawmills, planing mills,
furniture factories or the like, it is often necessary that the boards be
turned
upside down between different working operations or in order to carry out
quality inspection. Situations also arise when only certain boards in a batch
are to be turned over. Such turning of boards has hitherto largely been
carned out manually.
PROBLEM STRUCTURE
The present invention has for its object to devise the method disclosed by
way of introduction such that it permits a fully automatic turning of the
boards upside down. The present invention also has for its object to devise
the method such that only certain boards included in a batch are turned
over. The present invention further has for its object to devise the method
r such that the boards may be handled at great speed and with a high degree
of reliability without being damaged.
The present invention also has for its object to design the apparatus
intimated by way of introduction such that it is capable of turning all or
only
CA 02247136 1998-08-21
WO 9'7/30830 PCT/SE97/00234
2
certain boards included in a batch at great speed and with a high degree of
reliability, that the apparatus is simple and operationally reliable and is
also
economical in manufacture and in operation.
SOLUTION
The objects forming the basis of the present invention in respect of the
method will be attained if the method is characterized in that the boards are
moved forwards in a direction of movement in relation to the conveyor such
that the front edges of the boards are brought to the region of the rear side
of
the next dog in the conveyor, that lifting devices which are moved
synchronously with the conveyor are brought into engagement with the
undersides of those boards which are to be turned in the region at their front
edges, that the lifting devices are gradually raised, and that the boards are
subjected to a force in relation to the lifting devices forwardly in their
direction of movement, whereby the boards are caused to turn over with
their front edge facing upwards/ rearwards.
The objects forming the basis of the present invention in respect of the
apparatus will be attained if this is characterized by at least one second
conveyor which is substantially parallel with the first and has an upper part
at a slightly greater height than the upper part of the first conveyor, the
second conveyor operating at greater speed of movement that the first, and a
number of lifting devices which are disposed to move synchronously with
the first conveyor and to be liftable in the region behind the dogs of the
first
conveyor.
Further advantages will be attained according to the present invention if the
method is also given one or more of the characterizing features as set forth
in
appended subciaims 2 to 7 and if the apparatus is given one or more of the
characterizing features as set forth in appended subclaims 9 to I6.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The present invention will now be described in greater detail hereinbelow,
with reference to the accompanying Drawings. In the accompanying
CA 02247136 1998-08-21
WO 97!30830 PCT/SE97/00234
3
Drawings:
Fig. I schematically illustrates and apparatus for turning boards, seen
from the side, i.e. in the longitudinal direction of the boards;
and
Fig. 2 is a top plan view of the same apparatus as in Fig. 1.
DESCRIPTION OF PREFERRED EMBODIMENT
The apparatus according to the invention comprises a first conveyor 1 which
is intended for transporting boards 2 in a transport direction 3, kom the
right
to the left in the Figures. The first conveyor has a number of uniformly
spaced dogs 4 which, with their front sides 5, shunt the boards ahead of
them in engagement with the rear edges 6 of the boards. In such instance,
transport of the boards 2 takes place with the longitudinal direction of the
boards transverse to the longitudinal direction of the first conveyor and
transverse to the transport direction 3. Preferably, the longitudinal
directions
of the boards extend at right angles to both the transport direction 3 and the
longitudinal direction of the conveyor 1.
The first conveyor may include a number, preferably at least two, of parallel-
runrung chains, straps, belts or the Iike which are provided with the above-
disclosed dogs. The number of such chains etc., depends on the length of
those boards which are to be transported. Fig. 2 shows two such chains or
the Like.
The chains, straps or belts included in the first conveyor 1 run over wheels 7
and 8 which are supported on rotary shafts 9 and 10.
In addition to the chains, straps or belts included in the first conveyor,
this
conveyor may further include a number of longitudinally (along the
transport direction 3) disposed slide rails which vertically support the
boards 2 being transported. Instead of, or as a supplement to such slide
rails,
the chains etc. in the first conveyor may possibly have their upper regions
supported in longitudinal guides which may also carry the weight of the
CA 02247136 1998-08-21
WO 97130830 PCT/SE97/00234
4
boards.
The above disclosures as regards the cooperation of the first conveyor with ,
the advanced boards applies at the infeed end of the conveyor and at its
discharge end, i.e. at its right-hand and left-hand end, respectively. Along
the central region of the conveyor, i.e. along a turning zone, the situation
is
different in that the first conveyor here at least partly functions as a brake
which prevents the boards 2 in the transport direction 3 from being
displaced past predetermined positions, as will be described in greater detail
hereinbelow.
Within the turning zone, there is provided a second conveyor 11 which is
also designed as a chain conveyor, strap conveyor or belt conveyor or the
like. The second conveyor suitably has the same number of chains, straps or
I5 belts as the first conveyor, and these are disposed along and substantially
parallel with the corresponding chains etc. in the first conveyor 1. The
number of such chains etc. is adapted to the length of the boards 2 in the
same manner as that which applies to the first conveyor.
The second conveyor 11 has its upper part 12 located at a slightly greater
height than the upper part of the first conveyor 1. Further, the chains,
straps
or belts in the second conveyor are of a material which affords good friction
against the boards 2. I-iereby, the second conveyor (which advances at a
greater transport speed than the first conveyor 1) will subject the boards to
a
force in the transport direction 3 relative to the first conveyor. This
implies
that the boards 2 within the turning zone, i.e. the longitudinal extent of the
second conveyor 11, will be given higher speed by the second conveyor, so
that the boards, with their front edges 13, will come into abutment against
the rear edge 14 of the immediately preceding dog 4. This is clearly apparent
at the right-hand end of the second conveyor 11 in Fig. 1.
That disclosed above in respect of the slide rails, longitudinal guides etc.
in
connection with the first conveyor 1 applies with equal analogy also to the
second conveyor 11. It should also be observed that, regardless of the
detailed design of these slide rails, guides, etc., it applies that the second
conveyor carries the boards 2 at a height level which is slightly higher than
CA 02247136 1998-08-21
WO 97130830 PCT/SE97/00234
the first conveyor.
The width of the open space between adjacent dogs 4 on the first conveyor 1
a
is, for reasons which will be apparent below, approximately twice as large as
5 the maximum width of the boards 2 which are to be turned.
Within the turning zone, i.e. within the longitudinal extent of the second
conveyor 11, there is provided a third conveyor 15. This is disposed along
and beside the first conveyor 1 and preferably has the same number of
chains, straps, belts or the like as the first conveyor. The third conveyor 15
is
provided with a number of lifting arms or lifting devices 16 which move
synchronously with the first conveyor in its transport direction 3. The
lifting
devices 16 are disposed behind the rear edges 14 of the dogs 4 and are
disposed to be liftable within the turning zone.
In such cases where all boards 2 are to be turned, the lifting devices 16 may
be fixedly disposed on the third conveyor 15 in positions relative thereto
which are shown along the upper part of the third conveyor 15 in Fig. 1. This
implies that, because of the upward inclination in the transport direction 3,
the lifting devices 16 will be gradually raised within the turning zone.
In such cases where only certain boards 2 included in a batch are to be
turned, the lifting devices 16 are movably disposed on the third conveyor 15,
as will be described in greater detail hereinbelow.
It will be apparent from Fig. 1 that a lifting device 16a has just come into
engagement with the underside of a board which, with its front edge, abuts
against the rear edge 14 of a dog 4. The next lifting device 16b has raised
the
front portion of the board up and begins to turn the board over, with ifs
front
edge facing backwards. This turning of the board is facilitated by the fact
that the second conveyor 11 subjects the board to a force in the direction of
the transport direction of the first conveyor, i.e. in the direction of the
arrow
3. This force is generated by the second conveyor 11 in that this moves more
quickly than the lifting devices 16 so that the boards are shunted against the
lifting devices. As a result of this force, the turning or rotation of the
board
about its longitudinal axis is facilitated and supported. The lifting device
16c
CA 02247136 1998-08-21
WO 97/30830 PCTlSE97/00234
6
has just raised the front edge of the board so high that the board Ioses its
balance and is pivoted down backwards on the conveyor 11. For this
backward pivoting of the board to be possible, the distance between adjacent
dogs 4 should be approximately twice as large as the maximum width of
turned boards. It will further be apparent from Fig. 1 that the lower edge of
the board, which rests on the second conveyor, has been displaced in the
direction of the arrow 3, for which reason the lifting device 16c no longer
engages with the front edge of the board, now turned to face upwards, but
instead with the central portion of the original underside of the board.
Once the board has been finally turned upside down by the lifting device
16c, it will once again be given increased speed in relation to the first
conveyor 1, which is shown straight above the drive wheel 17 of the second
conveyor 11.
The third conveyor 15 is carried by shafts 18 and 29 which are located at
different heights so that the upper part of the third conveyor will thereby
slope upwards in its direction of movement, whereby the lifting devices 16
which follow the upper part of the third conveyor will gradually be raised.
In order to permit turning of only certain boards included in a timber batch,
the lifting devices 16 are suitably not permanently fixed in relation to the
third conveyor 15, but are secured in sleeves 20 which have their
longitudinal axes parallel with the parts of the third conveyor 15. The
lifting
devices 16 are pivotal in these sleeves, for which reason the lifting devices
16a, 16b and I6c are pivotal in accordance with the double headed arrow 21
about the pivot axis 24. Along the lower part, the lifting devices I6 are
naturally pivotal in a corresponding manner about an axis which is parallel
with the lower part of the conveyor.
The anchorage of the lifting devices 26 in the sleeves 20 disposed on the
third
conveyor is pivotal and without defined stops, for example in that the lifting
devices have conical portions which, under spring bias, are axially pressed
into corresponding conical apertures in the sleeves 20. ,
At the return areas of the third conveyor 15, there are provided guide rails
or
CA 02247136 1998-08-21
WO 97/30830 PCT/SE97100234
7
guides 22 and 23, where the guide 23 is disposed to open out the lifting
devices 16 which, along the lower part of the conveyor, are collapsed to a
state approximately parallel with the shafts 18 and 19, to outwardly pivoted
activated, upstanding positions which are shown along the upper part of the
conveyor. The guide 23 is movable between an active and opened position
where it pivots out the lifting devices 16 and a passive, collapsed position
where the lifting devices may pass without hindrance and without being
pivoted out to the active positions which are shown along the upper part of
the third conveyor. The guide 23 is coupled to a suitable prime mover for
permitting pivoting of all or only certain of the lifting devices,
corresponding
to turning of all boards or only certain boards, respectively.
The guide 22 at the upper end of the third conveyor is designed for opposite
pivoting of the lifting devices 16, i.e. for downward pivoting of them from
the upstanding, active positions along the upper part of the conveyor to
collapsed, substantially horizontal positions along the lower part of the
conveyor.
The above-described apparatus operates as follows:
Boards 2 are fed in at the right-hand end of the first conveyor 1 and rest
thereon or along slide rails or guides disposed with the conveyor. The
boards 2 are driven by the conveyor 1, at least along a certain part of its
length, in that the rear edges 6 of the boards abut against the front sides 5
of
the dogs 4 of the conveyor 1. When the boards 2 have arrived at the turning
zone, i.e. the longitudinal extent of the second conveyor 11, the boards are
displaced forwards in the transport direction 3 in relation to the first
conveyor 1. In such instance, the front edges 13 of the boards will strike the
rear edges 14 of the dogs 4 and be held urged against them, at least along a
certain portion of movement length of the second conveyor. The lifting
devices 16 are brought into engagement with the undersides of the boards 2
in the region of their front edges 13. The lifting devices 16 are disposed to
move synchronously with the first conveyor 1 and are located in the region
immediately behind, or at least in the proximity behind the rear edges 14 of
the dogs 4. Those lifting devices 16 which are to turn boards are disposed to
be raised gradually so that the font edge portions of the boards 2 are thereby
CA 02247136 1998-08-21
WO 97/30830 ECT/SE97/00234
8
lifted up. At the same time, the boards are subjected to a force relative to
the
first conveyor and the lifting devices, the direction of this force
corresponding to the transport drive direction 3 of the first conveyor.
Hereby, the boards 2 will be displaced in the transport direction at the same
time as their forward edge portions are lifted and braked and their
rear/ lower edges which rest on the upper part 12 of the second conveyor 11
are subjected to a shunting force so that the boards are thereby turned over
with their front edges facing upwards and backwards so far that the boards
are tilted backwards, with the original upper side facing downwards on the
upper part 12 of the second conveyor 21.
In order to ensure the above-mentioned engagement or force between the
boards 2 and the upper part 12 of the second conveyor 11, the boards are
lifted by this upper part in relation to the level of the upper part of the
first
conveyor 1.
Once the lifting devices I6 have turned the boards, they are once again
lowered to passive positions unless the intention is to turn all boards 2
included in a batch, since the lifting devices 26 are then suitably left in
their
opened, active positions or alternatively are fixedly mounted on the third
conveyor 15. During their movements in the opened, active position, the
lifting devices follow a path which is defined by a third conveyor 15 and
which makes an acute angle with the movement direction of the first and
second conveyors.
The present invention may be modified without departing from the spirit
and scope of the appended Claims.
