WORKPIECE TURNING APPARATUS

APPAREIL POUR RETOURNER LES PIECES A TRAVAILLER

English Abstract

This application relates to a self-contained apparatus for mechanically turning individual workpieces travelling on a conveyor, such as lengths of lumber travelling into or exiting from a sawmill. The invention reduces the need for lumber graders to turn lumber manually and thereby helps avoid repetitive motion injuries. The apparatus includes an adjustable height frame which is positionable alongside the conveyor. The frame supports a workpiece holder defining an open-ended slot for temporarily receiving an end portion of a workpiece. When the end of a lumber board or other workpiece is received within the holder, a proximity sensor causes the holder to rotate, thereby turning the workpiece lengthwise 180 degrees. The workpiece is then deposited on to the conveyor in its inverted orientation for further travel thereon. The apparatus may also optionally permit workpieces to pass through the holder when a "skip" rather than an "invert" signal is received. The workpiece holder may be connected to a rotatable shaft driven by an electric or hydraulic motor.

French Abstract

Cette invention concerne un appareil autonome pour le tournage mécanique de pièces mues par un convoyeur, telles que des pièces de bois débité entrant dans une scierie ou en sortant. L'invention réduit la nécessité de faire appel à des classeurs pour tourner manuellement le bois et, du coup, les risques de blessures découlant de mouvements répétitifs. L'appareil comprend un cadre de hauteur réglable qui peut être positionné le long du convoyeur. Le cadre supporte un support de pièce constitué d'une fente aux extrémités ouvertes conçue pour accueillir l'extrémité d'une pièce à travailler. Quand l'extrémité d'une planche de bois ou d'une autre pièce à travailler est logée dans le support, un détecteur de proximité déclenche la rotation du support, ce qui entraîne la rotation longitudinale de la pièce sur 180o. La pièce est ensuite déposée sur le convoyeur dans sa nouvelle orientation et poursuit son chemin. L'appareil peut également, de manière facultative, permettre aux pièces de passer par le support sans être tournées quand un signal pour « laisser passer » la pièce est communiqué plutôt qu'un signal pour la « tourner ». Le support peut être relié à arbre rotatif activé par un moteur électrique ou hydraulique.

Claims

11
WHAT IS CLAIMED IS:
1. An apparatus for turning a workpiece traveling on a conveyor
comprising:
(a) a workpiece holder for receiving an end portion of said
workpiece;
(b) a sensor for detecting the relative proximity of said workpiece
and said workpiece holder; and
(c) a rotation assembly for rotating said workpiece holder when
said workpiece is within said holder,
wherein said apparatus turns said workpiece from a first orientation to a
second orientation and deposits said workpiece on said conveyor in said
second orientation for further travel thereon.
2. The apparatus as defined in claim 1, wherein said workpiece holder
comprises first and second spaced-apart surfaces defining a slot
therebetween for receiving said workpiece, wherein said slot is open-
ended to permit passage of said workpiece into and out of said slot.
3. The apparatus as defined in claim 2, comprising a housing for
supporting said workpiece holder adjacent a side of said conveyor.

12
4. The apparatus as defined in claim 3, wherein said housing is height-
adjustable for varying the vertical position of said workpiece holder
relative to said conveyor.
5. The apparatus as defined in claim 1, wherein said second orientation
is inverted relative to said first orientation.
b. The apparatus as defined in claim 5, wherein said apparatus rotates
said workpiece lengthwise 180 degrees when turning said apparatus from
said first orientation to said second orientation.
7. The apparatus as defined in claim 2, wherein said rotation assembly
moves said workpiece holder between a first position wherein one of said
first and second surfaces is above said workpiece and the other of said first
and second surfaces is below said workpiece, and a second position
wherein said one of said first and second surfaces is below said workpiece
and said other of said first and second surfaces is above said workpiece.
8. The apparatus as defined in claim 7 , wherein rotation of said
workpiece holder is stopped when said workpiece holder moves from
said first position to said second position, thereby permitting said
workpiece to exit said slot in said second position.
9. The apparatus as defined in claim 2, wherein said sensor senses
when said workpiece has passed into said slot.
10. The apparatus as defined in claim 8, wherein said sensor senses

13
when said workpiece holder has moved to said second position.
11. The apparatus as defined in claim 7, wherein said rotation assembly
comprises a rotatable shaft coupled to an end of said workpiece holder
remote from said conveyor.
12. The apparatus as defined in claim 11, wherein said rotation
assembly comprises an actuator for periodically driving rotation of said
shaft.
13. The apparatus as defined in claim 12, wherein said actuator
comprises an electric motor.
14. The apparatus as defined in claim 12, wherein said actuator
comprises a hydraulic motor.
15. The apparatus as defined in claim 12, wherein said sensor is
operatively coupled to said actuator for actuating rotation of workpiece
holder when said workpiece holder is in said first position.
16. The apparatus as defined in claim 15, further comprising a controller
for controlling operation of said actuator, wherein said controller receives
input from said sensor.
17. The apparatus as defined in claim 2, wherein said first and second
surfaces extend in parallel planes and are spaced apart a sufficient distance
to permit an end portion of a length of lumber to pass through said slot.


14
18. The apparatus as defined in claim 1, further comprising a controller
for controlling operation of said rotation assembly, wherein said controller
receives input from said sensor.
19. The apparatus as defined in claim 2, wherein said first and second
surfaces are joined together at a location remote from said conveyor,
wherein said workpiece holder is U-shaped in cross-section.
20. An apparatus for turning a workpiece traveling on a conveyor
comprising:
(a) a housing positionable adjacent one side of said conveyor for
supporting a rotatable member;
(b) workpiece engagement means coupled to said rotatable
member and positionable overlapping a portion of said
conveyor for engaging an end portion of said workpiece;
(c) a sensor for sensing the presence of said workpiece proximate
said workpiece engagement means; and
(d) an actuator operatively coupled to said sensor for causing
rotation of said rotatable member and workpiece engagement
means,
wherein said apparatus turns said workpiece lengthwise 180 degrees and
releases said workpiece on to said conveyor for further travel thereon.


15
21. The apparatus as defined in claim 1, wherein said workpiece
engagement means comprises an open-ended slot sized to receive said
workpiece.
22. The apparatus as defined in claim 21, wherein said workpiece is slot
is positionable relative to said conveyor such that said workpiece is
capable of passing through said slot.
23. A method of turning a workpiece traveling on a conveyor
comprising:
(a) positioning a workpiece turning apparatus adjacent said
conveyor, said apparatus having a workpiece holder for
receiving an end portion of said workpiece;
(b) sensing when said workpiece has passed into said holder;
and
(c) rotating said workpiece holder to thereby cause rotation of
said workpiece lengthwise 180 degrees to an inverted
orientation.
24. The method as defined in claim 23, further comprising releasing
said workpiece on to said conveyor in said inverted orientation for
further travel thereon.
25. The method as defined in claim 23, further comprising controlling


16
rotation of said workpiece holder between first and second
positions, wherein said workpiece holder is capable of passing
through said workpiece holder in at least said first position.

Description

" ~ CA 02426549 2003-04-23
WORKPIECE TURNING APPARATUS
Technical Field
This application relates to a self-contained apparatus for
mechanically turning individual workpieces travelling on a conveyor, such
as lengths of lumber travelling into or exiting from a sawmill. The
invention reduces the need for lumber graders to turn lumber manually
and thereby helps avoid repetitive motion injuries.
Background
Quality control in sawmills is becoming increasing important.
Lumber graders are hired to examine lumber travelling on sawmill
conveyors to separate high quality lumber from lower quality grades. In
order to grade individual lumber pieces, the graders frequently need to
turn the lumber pieces. Over time this may result in repetitive motion
injuries such as carpo tunnel syndrome. Also, manually turning lumber
boards is time consuming and can distract the operator from the primary
task of grading the lumber.
Some mechanical lumber board turners are know in the prior
art to address this problem. Shark FinTM board turners available from
Redco Group are capable of turning boards individually. However, such
prior art board tamers require modification to the conveyor chain itself
(i.e. the mounting of pins or other actuators on the chain for engaging the
boards). The use of pin actuators takes up space on the conveyor, limits
conveyor speed and may require the use of a singulator to place the boards
on the conveyor chain in the required orientation. Moreover, such systems

CA 02426549 2003-04-23
2
are capable of rotating the boards in one direction only.
Devices are known in the patent literature for turning
workpieces travelling on a conveyor. United States Patent No. 4,798,278,
Cornacchia, dated January 17, 1989 discloses a conveyor for turning
packages upside down in a very gentle manner which eliminates the need
for any mechanism which grips the package in order to turn it. However,
the Cornacchia device is not adapted for engaging an end portion of the
workpiece or for optionally allowing the workpiece to travel through the
device.
United States Patent No. 5,482,140, Moore, dated January 9,
1996 relates to a rotary board inverter which relies on the motive force of
the boards themselves to invert the boards. 'The inverter is mounted
directly on the conveyor and does not include any means for skipping
inversion of selected boards.
United States Patent Nos. 5,836,438, Jung, dated November 17,
1998 and United States Patent Nos. 6,142,287, Biffert et al., dated
November 7, 2000 disclose other means for inverting, diverting or skipping
workpieces travelling on a conveyor. The Biffert et al. includes a servo
motor connectable to electronic control circuitry for rotating a pivot shaft.
The Jung and Biffert et al. devices are relatively complex and are not
adapted for engaging an end portion of a travelling workpiece.
The need has therefore arisen for an improved workpiece
turning apparatus which overcomes the limitations of the prior art.

CA 02426549 2003-04-23
3
Summary of Invention
In accordance with the invention, an apparatus for turning a
workpiece traveling on a conveyor is provided. The apparatus moves the
workpiece from a first orientation to a second orientation and deposits the
workpiece on the conveyor in the second orientation for further travel
thereon. The apparatus includes a workpiece holder for receiving an end
portion of the workpiece; a sensor for detecting the relative proximity of
the workpiece and the workpiece holder; and a rotation assembly for
rotating the workpiece holder when the workpiece is within the holder.
The apparatus includes a housing for supporting the
workpiece holder adjacent a side of said conveyor. The housing is height-
adjustable for varying the vertical position of the workpiece holder relative
to the conveyor. In one embodiment the apparatus is configured to rotate
the workpiece lengthwise 180 degrees when turning the workpiece from
the first orientation to the second orientation. Preferably the workpiece
holder comprises first and second spaced-apart surfaces defining a slot
therebetween for receiving the workpiece. The slot is open-ended to
permit passage of the workpiece into and out of the slot. The first and
second surfaces may be joined together at a location remote from the
conveyor such that the workpiece holder is U-shaped in cross-section.
The rotation assembly moves the workpiece holder between
a first position wherein one of the first and second surfaces is above the
workpiece and the other of the first and second surfaces is below the

CA 02426549 2003-04-23
4
workpiece, and a second position wherein the one of the first and second
surfaces is below the workpiece and the other of the first and second
surfaces is above the workpiece. Rotation of the workpiece holder is
stopped when the workpiece holder moves from the first position to the
second position, thereby permitting the workpiece to exit from the slot in
the second position. The sensor senses when the workpiece has passed
into the slot and is in the first or second positions.
The rotation assembly may include a rotatable shaft coupled
to an end of the workpiece holder remote from the conveyor. The rotation
assembly may include an actuator for periodically driving rotation of the
shaft. The actuator may comprise, for example, an electric or hydraulic
motor. Preferably the sensor is operatively coupled to the actuator for
actuating rotation of the workpiece holder when the workpiece holder is
in the first position. A controller receiving input from the sensor may also
be provided for controlling operation of the actuator.
Preferably the apparatus is adapted for turning lengths of
lumber traveling on a conveyor. In one embodiment, the first and second
surfaces extend in parallel planes and are spaced apart a sufficient distance
to permit an end portion of a length of lumber to pass through the slot.
In one particular embodiment the invention comprises an
apparatus for turning a workpiece traveling on a conveyor and includes
a housing positionable adjacent one side of the conveyor for supporting a
rotatable member; workpiece engagement means coupled to the rotatable
member and positionable overlapping a portion of the conveyor for

CA 02426549 2003-04-23
engaging an end portion of the workpiece; a sensor for sensing the
presence of the workpiece proximate the workpiece engagement means;
and an actuator operatively coupled to the sensor for causing rotation of
the rotatable member and hence the workpiece engagement means,
5 whereby the apparatus turns the workpiece lengthwise 180 degrees and
releases the workpiece on to the conveyor for further travel thereon.
A method of turning a workpiece traveling on a conveyor is
also described comprising:
(a) positioning a workpiece turning apparatus adjacent the
conveyor, the apparatus having a workpiece holder for
receiving an end portion of the workpiece;
(b) sensing when the workpiece has passed into the holder; and
(c) rotating the workpiece holder to thereby cause rotation of the
workpiece lengthwise 180 degrees to an inverted orientation.
In accordance with the method the workpiece is then released on to the
conveyor in the inverted orientation for further travel thereon.
Brief Description of Drawings
In drawings which illustrate embodiments of the invention
but which should not be construed as restricting the spirit or scope of the
invention in any way,

CA 02426549 2003-04-23
6
Figure 1 is an isometric view of the Applicant's workpiece
turning apparatus positioned alongside a lumber conveyor.
Figure 2 is an isometric view showing an end portion of a
length of lumber entering the workpiece holder slot of the apparatus of
Figure 1.
Figure 3 is an isometric view showing the workpiece holder
and length of lumber of Figures 1 and 2 rotated 90 degrees.
Figure 4 is an isometric view showing the workpiece holder
and length of lumber of Figures 1 and 2 rotated 180 degrees and showing
the lumber travelling out of the holder slot in an inverted orientation.
Descrytion of Invention
This application relates to a self-contained workpiece turning
apparatus 10 for mechanically turning individualworkpieces 12 travelling
on a conveyor 14. As shown in Figure 1, workpieces 12 may consist of
lengths of lumber travelling on conveyor 14 in the direction of the arrow
for delivering the lumber to or from a sawmill. The invention reduces the
need for lumber graders to turn lumber manually and thereby helps avoid
repetitive motion injuries. As will be appreciated by a person skilled in the
art, apparatus 10 could be similarly used to avoid manual turning of other
types of workpieces 12 travelling on a conveyor, such as manufactured
articles.

CA 02426549 2003-04-23
7
Apparatus 10 includes an adjustable height frame 16 which is
positionable alongside conveyor 14. Frame 16 supports a workpiece
holder 18 consisting of first and second spaced-apart plates 20 and 22
defining an open-ended slot 26 therebetween. Plates 20, 22 may be
connected together by a third plate 28 at a location removed from
conveyor 14 such that holder 18 is U-shaped in cross-section.
Frame 16 also supports a workpiece rotation assembly 30
which is coupled to holder 18. As illustrated in the drawings, rotation
assembly may include a servo motor 32 for driving rotation of a shaft 34
coupled to holder plate 28 by means of a coupling 36. A gear reducer 38
may be connected between motor 32 and coupling 36 for increasing the
torque which may be applied to workpiece holder 18 and to limit the load
applied to motor 32. Frame 16 also supports an electronic controller 40 for
controlling operation of rotation assembly 30 and hence turning of
workpiece 12, as described below.
Apparatus 10 further includes a sensor 42 for sensing when
workpiece 12 is in proximity to workpiece holder 18. In the illustrated
embodiment, sensor 42 is mounted on a support 44 extending underneath
holder 18 below the elevation of conveyor 14. Sensor 42 may comprise a
conventional laser beam emitter or the like.
In operation, frame 16 is positionable alongside conveyor 14
and is adjustable in height so that slot 26 of holder 18 is at the same
elevation as travelling workpieces 12. Slot 26 is of a sufficient size to
enable an end portion of each workpiece 12 to pass therethrough. As

CA 02426549 2003-04-23
8
shown in Figure 2, the passage of workpiece 12 into slot 26 is detectable
by sensor 42. For example, the presence of workpiece 12 within a central
portion of slot 26 could trip a laser beam or other light beam causing
sensor 42 to send a control signal to controller 40. Controller 40 then
triggers motor 32 to actuate rotation of rotatable shaft 34 connected to
workpiece holder 18 by coupling 36. This in turn causes rotation of holder
18 and workpiece 12 held within slot 26. Figure 3 shows workpiece 12
rotated lengthwise 90 degrees and Figure 4 shows workpiece 12 rotated
lengthwise 180 degrees to an inverted orientation relative to the
orientation of Figure 1. As shown in Figure 4, workpiece 12 is deposited
on conveyor 14 in the inverted orientation for further travel in the
direction of the arrow away from apparatus 10. As can be in Figures 2 and
4, workpiece passes into holder slot 26 through an open end thereof and
also passes out of slot 26 through an open end thereof. Holder 18 is then
in a position to receive the next-in-sequence workpiece 12.
In one embodiment of the invention, controller 40 may be
programmed to process a "skip" rather than an "invert" signal from
sensor 44 or some other input, including operator controlled input. In this
event, workpiece 12 may pass entirely through slot 26 (i.e into one open
end thereof and out the other open end) without triggering holder 18 to
invert the orientation of the workpiece 12. For example, controller 40
could be programmed (for example, using a counter) to turn every second
or third workpiece 12 rather than every single item. This functionality
could be used if multiple graders are positioned at different spaced-apart
positions on the same conveyor 14 (each grader using a corresponding
workpiece turning apparatus 10). Controller 40 could also be programmed

CA 02426549 2003-04-23
9
to turn workpiece 12 in either a clockwise or counter-clockwise direction
depending upon the application and the positioning of apparatus 10
relative to conveyor 14.
One advantage of workpiece turner 10 is that it is a self-
contained unit which can be installed alongside any conveyor 14. Unlike
prior art lumber turning systems, no modification to the conveyor itself is
required.
As will be appreciated by a person skilled in the art, other
means for actuating rotation of workpiece holder 18 could be substituted
in alternative embodiments of the invention. For example, workpiece
rotation assembly 30 could include a hydraulic motor and hydraulic
pumps) rather than an electric motor 32. Rotation of a rotatable shaft
connected to workpiece holder 18 could also be actuated by belts, pulleys
or the like. Mechanical rather than electronic means for stopping rotation
of workpiece 18 after the desired degree of rotation could also be provided.
Apparatus 10 could be used in conjunction with an optical
scanner for detecting defects in lumber boards or other workpieces
traveling on a conveyor. By way of example, an apparatus for inspection
and classification of attributes of a workpiece is described in United States
Patent No. 6,272,437 dated August 7, 2001. Controller 40 of apparatus 10
could receive input from such a lumber scanner or optimizer to automate
the process of deciding what boards to invert for subsequent optical
scaruling, operator inspection or downstream processing

CA 02426549 2003-04-23
As will be apparent to those skilled in the art in the light of the
foregoing disclosure, many alterations and modifications are possible in
the practice of this invention without departing from the spirit or scope
thereof. Accordingly, the scope of the invention is to be construed in
5 accordance with the substance defined by the following claims.

Representative Drawing