Note: Descriptions are shown in the official language in which they were submitted.
g7
-1-
MErHOD AND APPARATllS FOR OPlIMlZING
EDGE CU~ OF BOARDS FROM CANTS AND TH~ LlKE
Background and General Statement of the Invention
My invention pertains to a method and apparatus for determining
and positioning a cant in relation to edging saws or cutters, chippers, or band
saws to optimize the yield from the cant.
In the lumber industry it has been common practice to control the
position of a cant on a slat bed conveyor feeding edging saws by visual e-,aluation
of an operator, after which the cant is fed into the edging saws. This practice
results in low yield from the cant or boards with excessive wane resulting in
scrap. Production rate is controlled by the ability of the operator to judge andset the cant relative to the edging saws.
Sorenson U.S. 2,111,699 discloses the use of rnechanical fingers to
determine cant edge contour and direct positioning of the cant on the conveyor
feeding edging saws. Barr et al. U.S. 3,931,501 discloses photoelectric cell
sensors for surface defect detection by passing the detectors longitudinally over
the work piece lengths.
The manual positioning of the cant in relation to the ednging saws
is slow and tedious and subject to operator mistakes. The mechanical
determination of the edge contour does not provide for de~ermination of the
maximum yield that can be obtained from a given cant. It is the gener~l object
of the present invention to provide a method and appratus which will achieve thepurpose of determining the maximum usable material from a cant and directing
the position of that cant in relation to edging saws.
Another object of this invention is the provision of equipment that
will determine maximum cant yield at a high rate of speed.
Another object of this invention is to provide for edge sensing that
is not affected by color.
Another object of this invention is to provide cant edge sensing
that is not affected by normal vibration, dust and dirt.
Another object of this invention is to provide cant edge sensing
1697
.,
-2-
units requiring a minimum of space.
Another object of this invention is to pr~vide cant edge sensors
that are accurate independent of the cant surface that f Ices upwardly.
Another object of this invention is to provide cant edge sensors
that will sense the surface edge of center cants.
Another object of this invention is to determine the maximum
production from a given cant and position the cant in relation to edging saws toyield that production.
Another object of this invention is the provision of equipment that
is highly accurate.
Broadly considered the foregoing and other objects of this invention
are accomplished by a method which comprises positioning a plurality of
proximity sensors relative to the surface of a cant, conveying the cant past thesensors, encoding a series of pulses into a computer during the time the cant ispassing the sensors, determining the position to set the cant relative to edgingsaws to optimize cant yield, directing a pair of positioning heads to position the
cant in relation to the edging saws and transferring the cant to a longitudinal
conveyor for feeding the edging saws.
The objects of the invention are further achieved by providing an
apparatus for accomplishing the foregoing functions. More specifically, the
invention includes apparatus for positioning a cant r~lative to edging saws,
of electric pulse signals; d) a plurality of pneumatic e~ge sensors spaced apartlaterally on lines substantially perpendicular to the direction of movement of the
feed conveyor means for directing jets of air under pressure toward and
substantially perpendicular to said cant support plane, said pneumatic edge
sensors being operable upon impingement of air jets therefrom upon the leading
edge of the confronting surface of a cant to initiate the delivery to the computer
of electric pulse signals from the source thereof correlated with the rate of
movement of the feed conveyor and upon passage of the trailing edge of the cant
from said air jets to stop the delivery of said electric pulse signals to the
computer, for determining the widths of the upper and lower surfaces of the
cant; e) longitudinal conveyor means for transporting the cant through edging
saws; and, f) cant transport means operable by the computer for positioning the
cant on the longitudinal conveyor means relative to the edging saws for obtaining
maximum cant yield.
The invention also includes a cant movement and aligning mechfl-
nism for transversely moving a cant from a delivery position to a position on a
conveyor such that the cant is longitudinally aligned in a predetermined manner
. ~ .
`~ 9~
,~-2a-
with cutters adapted to longitudinally cut the cant, said cant movement and
aligning mechanism comprising: overhead support means, overlying said delivery
position and said conveyor, for supporting at least two positioning heads for
movement in a direction transverse to said longitudinal axis along which cants
are to be cut; at least two positioning heads mounted on said overhead support
means for movement in a direction transverse to the longitudinal axis along
which cants are to be cut; positioning means connected to said at least two
positioning heads for moving said at least two positioning heads between a
position whereat at least a portion of said positioning heads lies beyond the edge
of said cant remote from said conveyor when a cant is in said delivery position
and a position whereat said at least two positioning heads generally overlie said
conveyor; at least two pairs of vertically oriented piB, one pin of each of saidpairs forming a pusher pin and the other pin of each of said pairs forming a hold
down pin, one of said pairs being mounted in each of said positioning heads, such
that the pusher pin is mounted in the portion of the positioning head movable to a
position beyond the edge of a cant remote from said conveyor when a cant is in
said delivery position and the hold down pin is mounted in the positioning head
between the pusher pin and the conveyor; extension and retraction means
connected to said pusher and hold down pins for vertically extending and
retracting said pusher and hold down pins; and, control means connected to said
positioning means and said extension and retraction means for: moving said at
least two positioning heads with said`pusher and hold down pins retracted, to a
position such that said pusher pins lie beyond the edge of a cant remote from said
conveyor when a cant is in said delivery position; extending said pusher and hold
down pins such that the lower end of said pusher pins lie below the upper surface
of a cant at said delivery position and the lower end of said hold down pins lieatop the upper surface of a cant at said delivery position; and, moving said at
least two positioning heads tGward said conveyor so that said pusher pins impinge
on the edge of a cant remote from said conveyor and move said cant towards said
conveyor until said cant reaches a predetermined position above said conveyor,
said predetermined position being such that said cant is longitudinally aligned in
a predetermined manner with said cutters.
Brief Description of the Drawin~s
Fig. 1 is a schematic elevation view showing the functional
elements.
Figs. 2 through 13 are schematic illustr ~tions of the functional
steps.
Figs. 14 and 15 are alternate configurations of the cant.
`~ 11;~1697
-2b-
Fig. 16 is a plan view along the line 16-16 of Fig. 1
Figs. 17A and 17B are sectional elevation views taken along the
line 17-17 of Fig. 16.
Fig. 18 is a fragmentary elevation view along the line 18-18 of Fig.
17A.
Fig. 19 is a fragmentary cross-section elevation along the line
19-19 of Fig. 18.
Fig. 20 is a partial cross-section along the line 20-20 of Fig. 18.
Fig. 21 is a schematic cross-section Plong the line 19-19 of Fig.
18.
Fig. 22 is a fragmentary plan view of the invention.
Fig. 23 is a fragmentary cross-sectional elevation along the line
23-23 of Fig. 22.
':
,~,r ,~
i:
, .
...
:
'' : ` :~
697
Fig. 24 is a fragmentary elevation along the line 24-24 of Fig. 16.
Fig. 25 is a fragmentary cross-section elevation along the line
25-25 of ~ig. 24.
Fig. 26 is a block diagram illustrating the electrical computer
interconnections.
Description of Specific Embodimen s of the Invention
The principal sequence of events is illustrated in Figs. 1 through 13
in which the cant 2 is positioned on a feed conveyor 4 Figs. 1 and 2, measuring
the thickness by a thickness detector 5 and positioning proximity sensor units 6relative to the cant surface, Fig. 3, conveying the cant 2 past lower and upper
sensors 7 and 6 respectively sensing the lower and upper cant leading edges Figs.
4 and 5 to initiate a series of pulses to a computer and sensing the lower and
upper cant trailing edges Figs. 6 and 7 to stop the pulses thereby determining the
cant width. The computer determines optimum cant yield for the cant thickness
and width as positioning heads 8 return to the discharge of the feed conveyor 4
Fig. 8. The computer directs the positioning heads to lower pusher pins 130 Fig.9 and hold down pins 132 Fig. 10, position the cant 2 relative to longitudinal
conveyor 9 Fig. 11, withdraw pusher pins and hold down pins Fig. 12 and transferthe cant to the longitudinal conveyor 9 Fig. 12 for feeding into edging saws 10
Fig. 13.
The apparatus, with particular reference to the drawings, to
accomplish the sequence is supported on a frame 11 Fig. 16 having longitudinal
members 12, transverse members 14 and vertical members 16 Figs. 17A and 17B.
The apparatus supported by the frame comprises the following.
A. Cant Volume Measurement
The feed conveyor 4 Figs. 16 and 17A comprises a plurality of
parallel chains 18 driven by sprockets 20 supported on a common shaft 22 driven
by a hydraulic motor, not shown. The chains 18 are provided with spaced lug
links 18a adapted to contact the trailing edge of the cant 2. A pulse generator
24 shown in block form in Fig. 26 comprises a timing belt driven by the feed
conveyor drive thereby establishing a direct relation between the conveyor speedand the pulse intervals to be employed by the computer in determining the cant
width.
Positioned above the feed conveyor is a thickness detector 5 Fig.
16 eomprising a wheel 26 mounted on a pivoted arm 28 supported by bracket 30
from frame member 12b. Connected to the pivot shaft is a potentiometer 32.
Positioned between longitudinal frame members 12a and 12b Fig.
17A are longitudinally spaced hold down shoes 34 having upward extending arms
~, .
11;~1697
--4--
34a and 34b and an upward sloping forward edge 34c. Extending longitudinally
between and parallel to frame members 12a and 12b are shafts 36 and 38
supported by frame brackets 37 and 39 respectively. Secured to the shafts 36
and 38 are lever arms 40. Pins 42 connect the lever arms 40 to the upward
extending arms 34a and 34b of the shoes 34 providing support of the shoes by theshafts 36 and 38. Secured to the shafts 36 and 38 are upward extending arms 44
and 46 respectively, interconnected by link member 48 through pins 50, thereby
producing vertical movement of the shoes 34 by movement of the link member
48. An upward extension 48a of the link member 48 provides for a pin
connection 52 to the piston rod 54 of the cylinder assembly 56. The cylinder
assembly 56 is pivotally supported at its opposite end on bracket 58 extending
from longitudinal frame member 12a. Mounted on the cylinder assembly 56 is a
position sensing potentiometer 60 actuated by rack 62 connected to piston rod
54. The potentiometer 60 functions in conjunction with potentiometer 32. The
cylinder assembly 56 comprises a double acting hydraulic cylinder portion 56a
and a single acting pneumatic portion 56b. The position of the piston rod 54 is
directed by the signal of the thickness gauge potentiometer 32 thereby
'J establishing the position of the lower edge of the shoes 34 relative to the upper
surface of the cant 2, the shoes normally being positioned slightly above the
upper cant surface. The pneumatic portion 56b of the cylinder assembly 56
provides a cushion in the event the shoes 34 are positioned below the cant
surface.
Slidably supported in longitudinal frame member 12c Fig. 17A are a
plurality of sensor units 6 comprising a sensor tube 64 supporting in the lower end
a pneumatic proximity sensor 66 Fig. 18. Projecting vertically from the
longitudinal frame member 12c between the positions of the sensor tubes 64 are
guides 67 Figs. 22 and 23, which slidably position bar 68 having guide bushings 70.
The upper end of each sensor tube 64 extends through clearance holes in the bar
68 and is provided with a vertical positioning nut 72 pinned to the sensor tube 64.
Alignment of the sensor tubes 64 is provided by upward projecting members 68a
positioned in close proximity to the flat side of the nuts 72. Nut adjustment isaccomplished by raising the sensor tube so the nut 72 clears member 68a. The
bar 68 is supported in its vertical position by angular bracket 68b in contact with
wheel 74 on the upward extending arms 34a of the shoes 34, thereby fixing the
relation of the sensor unit 6 relative to the shoes 34 between the passing of cants
2 under the sensor units.
Surrounding the lower end of each sensor tube 64 is a sensor shield
76 Fig. 19 having lower sloping surfaces 76a and 76b which provide for the cant
1697
--5--
to raise the sensor tube as it contacts the shield 76. The shield 76 establishes the
minimum space between the pneumatic proximity sensor 66 and the cant 2
surface. The sensor tube nut 72 is adjusted to permit the lowest point of the
shield 76 to be below the lower surface of the shoes 34 by an amount that assures
the shield contacting the cant. The clearance shown in Fig. a3 between the nut
72 and the bar 68 is the vertical rise of the sensor tube when the shield 76 is in
engagement with the cant surface. The sensor unit maintains the shield in
contact with the cant by gravity.
A plurality of lower sensor units 7 having a sensor tube 78 are
slidably supported on lower longitudinal frame member 12d Fig. 17A. Mounted in
the upper end of each sensor tube 78 is a pneumatic proximity sensor identical
with the upper pneumatic proximity sensor 66, surrounded by identical shield 76.The vertical axis of sensor tubes 78 are offset from the vertical axis of sensortubes 64 to avoid pneumatic flow interference.
The sensor tube 78 is supported vertically with the shields 76 held
in contact with the cant 2 by compression spring 80.
The maximum upward position is sdetermined by the nut 72
positioned and pinned on the sensor tube 78. The sensor tube is held in alignment
by the close proximity of the flat side of nut 72 with brackets 82 secured to the
frame member 12d, as explained for the upper sensor tubes 64.
Mounted between a pair of sensor tubes 78 and positioned forward
and rearward of the line of the sensor tubes are a pair of photoelectric cells 84
Fig. 17A. Aligned with and supported by longitudinal frame member 12c between
a pair of upper sensor tubes 64 are light sources 86. These photoelectric cells
function in coordination with the thickness detector potentiometer 32 and the
shoes 34 positioning potentiometer 60 associated with cylinder 56 to control thevertical position of shoes 34 during the absence of a cant between sensor uints 6
and 7
The pneumatic proximity sensor 66 is a standard unit that functions
as an edge sensor in my invention. A source of 6 psi air employing longitudinal
frame members 12e and 12f Fig. 17A as a conduit and 3 psi air from pipes 88 and
89 are supplied to monitor units 90 Figs. 16 and 26. Several sensors 66 are
provided with air and monitored from each monitor unit. The 6 psi air flows fromannular orifice 66a Fig. 21. The 3 psi air flows from center orifice 66b. The
orifices are vertically spaced from the cant surface by the shield 76 provided
with a relief slot 76c. When the edge of the cant interferes with air flow from
the annular orifice 66a a back pressure is developed in the center orifice 66b
causing an increase in the 3 psi pressure. The increase in pressure causes an
,
.,
. s,.
:
.
. . .
:-'
. .
,,
97
-6-
electrical signal to the computer Fig. 26 to begin register of the pulses from the
pulse generator 24, previously mentioned. Recording of pulses by the computer
are stopped when the sensor air flow is no longer interfered with thereby
permitting the computer to establish cant width at each sensor position.
During the remaining travel time of the cant 2 on conveyor chains
18 the computer Fig. 26 combines the information from the thickness detector
potentiometer 32 and the sensor units 6 and 7 to determine the edge cut that will
produce maximum cant yield.
B. Cant Edges Saw Alignment
Transverse frame members 14a Figs. 16, 17A and 17B provide skid
surfaces on the plane of the upper edge of conveyor chains 18 onto which the
cant 2 is discharged.
The longitudinal conveyor 9 Fig. 11 comprises a series of slat bar
conveyors 92 Figs. 16, 17B, 22 and 24 having their travel transverse to conveyorchains 18 and spaced from the discharge end of conveyor chains 18 with the top
of the slat bars below the upper surface of chains 18 and frame members 14a.
Between the slat bar conveyors and transverse to the conveyor travel are lift
skids 94. The lift skids 94 are slidably supported in frame slots and raised andlowered by double acting pneumatic cylinders 96 supported on transverse frame
member 14b. In the raised position the upper edge of the lift skid 94 becomes anextension of the upper surface 15 of the frame members 14a.
Each slat bar conveyor comprises a pair of chains 92a Figs. 16, 17B
and 24 to which the slat bars 92b are attached. The chains 92a are supported on
and driven by sprockets 92c driven by variable speed hydraulic motor, not shown.During the upper horizontal travel the slat bars 92b are supported on skids 98 and
100. The skids are adjusted vertically by the screws 102 threaded through bars
104 attached to frame members Fig. 25. The skids 100 are provided with an
r' inverted V Fig. 17B to engage an inverted V-notch in the lower side of slat bars
92b to assure straight travel of the slat bars. The several sets of slat bar
conveyors function as longitudinal conveyor 9 for the cant 2 to be fed into the
edging saws 10.
Slidably supported above the conveyor chains 18, surface 15, and
conveyors 92 are positioning heads 8 Fig. 9 comprising identical positioning heads
106 and positioning head 108 Figs. 16, 17B and 24. The positioning heads are
provided with guide bearings 110 to slidably support the positioning heads on
guide rods 112 attached at their ends to longitudinal frame mebers 12a Fig. 17A
and 12g Fig. 17B.
Positioning heads 106 are positioned along the guide bars 112 by
'.~
.: .
... .
11;~1697
--7--
racks 114 attached to the positioning heads and driven through gear boxes 116 byhydraulic motor 118 Fig. 16 and 17B. Associated with the motor 118 is a logio
unit 120 that controls the heads position.
Similarly, positioning head 108 is positioned by rack 122 driven
through gear box 124 by hydraulic motor 126 controlled by logic unit 128 Figs.
16 and 26.
Each positioning head is provided with a pusher pin 130 that
engages the trailing edge of the cant and a hold down pin 132 that engages the
upper surfaces of the cant. The pusher pins 130 are actuated by a double acting
pneumatic cylinder 130a and hold down pins 132 are actuated by a double acting
pneumatic cylinder 132a. The pusher and hold down pins of one of the positioningheads 106 are used in combination with the pusher and hold down pins of
, positioning head 108, the particular positioning head 106 to be used being
determined by the cant length.
The positioning head 108 in combination with one of the positioning
heads 106 position the cant 2 on lift skids 94 as directed by the computer to align
the cant with the edger saws 10 Fig. 13. Hold down wheels 134 are
pheumatically actuated to contact the cant after which the pusher pins 130 and
hold down pins 132 are raised from the cant. The lift skids 94 are lowered
transferring the cant to the slat bar conveyors 92.
- C. Operation
In operation the cant 2 is placed on feed conveyor chains 18 with
its longitudinal axis transverse to the travel of conveyor chains 18. The lugs 18a
of conveyor chains 18 engage the trailing edge of the cant 2 transporting the
cant under thickness detector wheel 26 Figs. 1 and 16 changing the position of
potentiometer 32 establishing an input to the computer Fig. 26 and initiating
instructions to the hydraulic cylinder 56a to position shoes 34 relative to the cant
2 upper surface. The rack driven potentiometer 60 associated with shoe
positioning cylinder 56 indicates the proper position of the shoes 34 to the
, computer and places the upper sensor tube 64 shield 76 in position to contact the
; upper cant surface.
The conveyor chains 18 transport the cant 2 between the upper and
lower sensor tube shields 76 Fig. 17A causing sensors 66 to initiate a series ofpulses, having a pulse interval related to the conveyor speed, to be counted by
the computer for each of the sensor units 6 and 7.
As the trailing edges of the cant 2 are transported past the sensor
-; units 6 and 7 the pulse counting recording is stopped, establishing the width of
the upper and lower cant surfaces at each sensor unit.
:
,'"
.
,
,
:.
.,:,. ~ ;. : ;
11;~1697
? 8
The computer combines the information from the thickness
detector potentiometer 32 with the cant width pulses and determines the
alignrnent of the cant 2 with respect to the edging saws 10 ior optimum cant
` yield as the cant 2 is pushed onto skid 15 by the conveyor chain lugs 18a.
The computer directs the logic units 120 and 128 Figs. 16 and 26 to
energize motors 118 and 126 to move the positioning heads to a position for
lowering the pusher pins behind the trailing edge of cant 2. The computer then
directs one of the positioning heads 106 and positioning head 108 to lower theirrespective pusher pins 130 behind the trailing edge of the cant 2 Fig. 17B. The
; computer then directs the position heads to move toward the slat bar conveyors
92 into contact with the traling edge of the cant when the hold down pins 132 are
energized to contact the upper cant 2 surface.
~ The computer through logic units 120 and 128 controlling motors
; 120 and 126 positions the cant 2 on lift skids 94 in alignment with the edging
saws 10.
- The computer directs the hold down wheels 134 to lower onto the
cant and to raise pusher pins 130 and hold down pins 132 from the cant 2 and to
lower lift skid 94 by energizing cylinder 96 transferring the cant 2 to the slat bar
conveyors 92 which move the cant longitudinally into and through edging saws 10.
: '
~,
.t:
'
., '
: ;
b
,''''
." .,,i "
.
" ' ' ' ' . ' ~ ,
': ' '
