U.S. patent number 3,890,509 [Application Number 05/440,505] was granted by the patent office on 1975-06-17 for automatic edger set works method and apparatus.
This patent grant is currently assigned to The Black Clawson Company. Invention is credited to Carl W. Maxey.
United States Patent |
3,890,509 |
Maxey |
June 17, 1975 |
Automatic edger set works method and apparatus
Abstract
Method and apparatus for scanning lumber, particularly cants,
for determining the configuration thereof includes first and second
light sources for directing beams of light at a low angle of
incidence across the cant. The light reflected from the cant at a
plurality of locations provides information on the amount and
orientation of useable wood within the cant. This information may
be used to orient the cant prior to sawing into studs. By proper
orientation and positioning of the cant relative to the saws,
maximum yield from each cant may be realized.
Inventors: |
Maxey; Carl W. (Everett,
WA) |
Assignee: |
The Black Clawson Company
(Hamilton, OH)
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Family
ID: |
26941840 |
Appl.
No.: |
05/440,505 |
Filed: |
February 7, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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251809 |
May 9, 1972 |
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Current U.S.
Class: |
250/559.25;
144/357; 144/379; 250/223R |
Current CPC
Class: |
B27B
1/00 (20130101); B27B 31/06 (20130101); G01N
21/8986 (20130101) |
Current International
Class: |
B27B
1/00 (20060101); B27B 31/06 (20060101); B27B
31/00 (20060101); G01N 21/86 (20060101); G01n
021/30 () |
Field of
Search: |
;144/312,313
;250/223,560,559,561 ;356/199,201 ;209/111.7 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lawrence; James W.
Assistant Examiner: Nelms; D. C.
Attorney, Agent or Firm: Biebel, French & Bugg
Parent Case Text
RELATED APPLICATION
This application is a continuation of application Ser. No. 251,809,
filed May 9, 1972, now abandoned.
Claims
What is claimed is:
1. A method of scanning cants having leading and trailing wanes to
obtain the maximum yield therefrom including the steps of
directing a beam of light at an angle of incidence across said cant
such that a sawn portion and the trailing wane are illuminated and
the leading wane is placed in shadow,
directing a second beam of light across said cant at an angle of
incidence such that said sawn portion and the leading wane are
illuminated and the trailing wane is placed in shadow, and
sensing the light reflected from said cant at a plurality of
locations to provide information on the location of the leading and
trailing edges of the cant and the leading and trailing edge of the
sawn portion,
whereby the locations of the sawn portion of the cant and the
leading and trailing edges of the cant are identified at said
plurality of locations.
2. Apparatus for scanning a cant optically to provide information
regarding the location of the leading and trailing edges of the
cant and a sawn portion thereof comprising
conveyor means including a pair of indexing lugs adapted to engage
the leading edge of the cant,
means for directing a first source of light at an angle of
incidence across a cant for illuminating the sawn portion thereof
and the trailing wane,
means for directing a second source of light at an angle of
incidence across said cant for illuminating the sawn portion
thereof and the leading wane,
a plurality of photodetectors positioned to sense the location of
the leading and trailing edges of the sawn portion and the leading
and trailing edges of the cant at said plurality of locations by
observing the light reflected from said first and second light
sources, and
circuit means responsive to the outputs of said plurality of
photodetectors for locating the leading and trailing edges of the
cant and the leading and trailing edges of the sawn portion with
respect to said lugs.
3. Apparatus of claim 2 wherein said plurality of photodetectors
includes a first set positioned to receive light reflected by said
cant from said first source thereby sensing the location of the
leading edge of the sawn portion and the trailing edge of the cant,
and a second set positioned to receive light reflected by said cant
from said second source thereby sensing the location of the
trailing edge of the sawn portion and the leading edge of the
cant.
4. Apparatus of claim 3 further including a light screen positioned
between said first and second sets of photodetectors to prevent the
first and second sources from illuminating said cant and reflecting
light into said second and first set of photodetectors,
respectively.
5. Apparatus of claim 2 wherein said plurality of photodetectors
are mounted in a line substantially perpendicular to the direction
of movement of said cant, said apparatus further including means to
energize said first and second sources of light alternatively.
6. Apparatus for scanning a cant optically to determine the
location of the leading and trailing edges of the cant and the sawn
portion thereon, comprising
a first source of light for illuminating the sawn portion and the
trailing wane of the cant,
a second source of light for illuminating the sawn portion and the
leading wane of the cant,
a plurality of photodetectors positioned to sense the location of
the leading and trailing edges of the sawn portion and the leading
and trailing edges of the cant at a plurality of locations across
the cant by observing light reflected from said first and second
light sources,
means for causing relative movement of the cant with respect to
said photodetectors, and
means for providing information regarding the position of the cant
relative to said photodetectors.
7. A method of optically scanning cants having a sawn portion and
leading and trailing wanes including the steps of
directing a beam of light at an angle of incidence across said cant
such that at least the trailing wane is illuminated and the leading
wane is placed in shadow,
directing a second beam of light across said cant at an angle of
incidence such that at least the leading wane is illuminated and
the trailing wane is placed in shadow, and
sensing the light reflected from said cant whereby the location of
the leading and trailing edges of the cant and the leading and
trailing edge of the sawn portion may be determined.
8. A method of optically scanning cants having a sawn portion and
leading and trailing wanes including the steps of
directing a beam of light at an angle of incidence across said cant
such that at least the trailing wane is illuminated and the leading
wane is placed in shadow,
directing a second beam of light across said cant at an angle of
incidence such that at least the leading wane is illuminated and
the trailing wane is placed in shadow,
moving the cant with respect to a plurality of light sensing means
positioned above the cant, and sensing the light reflected from
said cant with respect to the position of the cant as it moves
relative to the light sensing means whereby the location of the
leading and trailing edges of the cant and the leading and trailing
edge of the sawn portion may be determined.
9. Apparatus for optically scanning a cant having a sawn portion
and leading and trailing wanes to provide information regarding the
configuration thereof, said apparatus comprising
means for directing a first source of light at an angle of
incidence across a cant for illuminating at least the trailing
wane,
means for directing a second source of light at an angle of
incidence across said cant for illuminating at least the leading
wane,
a plurality of photodetectors positioned to sense the location of
the leading and trailing edges of the sawn portion and the leading
and trailing edges of the cant at said plurality of locations by
observing the light reflected by the cant from said first and
second light sources, and
conveyor means for moving said cant relative to said
photodetectors,
circuit means responsive to the outputs of said plurality of
photodetectors for locating the leading and trailing edges of the
cant and the leading and trailing edges of the sawn portion with
respect to said conveyor means.
10. Apparatus of claim 9 wherein said conveyor means includes a
pair of indexing lugs adapted to engage the leading edge of the
cant to provide a reference against which the location of the
leading and trailing edges of the cant and the leading and trailing
edges of the sawn portion of the cant is measured.
11. The apparatus of claim 10 wherein said conveyor means further
includes a tachometer generator to sense its rate of movement.
Description
BACKGROUND OF THE INVENTION
In processing lumber, and particularly the manufacture of studs
from log blocks, the logs are usually manually oriented prior to
being fed through bandsaws which cut the log into cants of either
two or four inch thicknesses. The cants are then moved to ganged
edgers where they are further cut into studs, thereby yielding
either 2 .times. 2, 2 .times. 4, or 4 .times. 4 inch studs. The
material which remains, either in the form of sawdust or chips, is
of less monetary value than the studs, and therefore it becomes
apparent that obtaining the maximum number of studs from a given
log block will not only increase profitability, but will also
maximize the utilization of natural resources.
SUMMARY OF THE INVENTION
This invention relates to a method and apparatus for scanning
lumber, particularly cants, and orienting the cants with respect to
saws to obtain therefrom the most useful and profitable material
and to minimize waste of natural resources.
More particularly, this invention includes an optical scanner in
which a first beam of light is directed at a low angle of incidence
across the cant to illuminate the sawn portion and trailing wane
and at the same time place the leading wane in shadow. A second
beam of light is directed across the cant, also at a low angle of
incidence, to illuminate the sawn portion and the leading wane,
with the trailing wane being placed in shadow. The first and second
light sources may be operated continuously, in which case an
optical barrier will be used to prevent both the leading and
trailing wanes from being illuminated at the same time. In another
embodiment, the first and second light sources are alternately
switched on and off thereby allowing a single set of light
detectors to be used to sense the light reflected from the cant at
a plurality of locations in a direction transverse to its direction
of movement.
In the preferred embodiment, a plurality of photodetectors are
positioned directly above the cant to observe the light reflected
therefrom as the cant is moved by a conveyor. A tachometer or other
pulse producing means is attached to the conveyor to provide
information regarding to the position of the cant relative to the
detectors. The conveyor includes lugs which engage the leading edge
of the cant thereby to provide a reference against which all
measurements are made.
At each of the plurality of locations across the cant being
observed by a photodetector, the leading and trailing edges of the
cant will be determined along with the leading and trailing edges
of the sawn portion of the cant. This information is processed by a
computer which is adjusted to determine the proper orientation and
position of the cant with respect to chippers and ganged edgers to
obtain maximum yield from each cant.
The output of the computer adjusts the position of alignment means
mounted in line with the lugs on the conveyor. These alignment
means adjust both the orientation and lateral position of the cant
with respect to a fixed chipper. An adjustable chipper is
positioned by the computer to remove wood from the opposite edge of
the cant, and the cant is then moved through the chippers and then
into the ganged edgers.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a stud mill in which the method and
apparatus of this invention may be utilized;
FIG. 2 is a perspective view of a portion of a log block and the
location of saw cuts which may be made to produce a plurality of
cants;
FIG. 3 is a diagrammatic illustration of a cant scanning station
showing first and second light sources and a plurality of
photodetectors for sensing the light reflected from a cant as it is
moved by a conveyor, and also an electrical block diagram of a
control circuit for orientating the cant and adjusting the cant
chippers;
FIG. 4 is an elevational view of one embodiment of a cant scanning
device constructed according to this invention;
FIG. 5 is a plan view of the cant scanning device of FIG. 4;
FIG. 6 is a detailed view of the scanning section of the cant
scanner of FIG. 4; and
FIG. 7 shows the measurements made by the cant scanning device of
FIGS. 3-6 with respect to a reference line.
FIG. 8 is an elevational view showing another embodiment of the
invention where a single set of photodetectors is used and the
light sources are alternately switched on and off.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, and particularly to FIG. 1, a stud
mill is shown into which logs 10 are moved by means of a conveyor
12 onto V-blocks 13 and then past an optical scanner 15 where log
diameter is measured at a plurality of positions throughout its
length. If the logs are not of acceptable quality, they are carried
by conveyors 17 and 18 to the exterior of the mill. If the logs are
of acceptable quality, they are received by a carriage mechanism
20.
The logs 10 may be rotated manually in order to present the optimum
profile prior to scanning by an optical scanning device 15. The
output of the optical scanner 15 is applied to circuit means, such
as a properly programmed general purpose computer, which takes this
information and determines the maximum number of studs which may be
cut from the log. The computer therefore takes into consideration
the fact that the log will first be cut into cants of either two or
four inch thickness. In the embodiment shown, the center cut will
be four inches thick since the carriage 20 is in excess of two
inches.
The logs 10 are then moved to the right, as viewed in FIG. 1,
between slab chippers 22 and 23, both of which are adjustable
relative to the carriage 20 under the direction of the computer.
These slab chippers will form faces 24 and 25, respectively, on the
log 10, as shown in FIG. 2.
The log is then carried by the carriage 20 through adjustably
positionable bandsaws 28 and 29 which will make cuts 31 and 32,
respectively, in the log to form cants which then separate
themselves from the log and are carried are conveyors 33 and 34 to
pans 35 and 36. Whether the cuts 31 and 32 are made two or four
inches from the surfaces 24 and 25 will be determined by the
computer in order to yield the maximum number of studs of
acceptable width and length from any given log.
The bandsaws 28 and 29 are then repositioned under the direction of
the computer, and the carriage then moves the log through the
bandsaws in the opposite direction to form cuts 37 and 38. The
resulting cants are then carried by transfer conveyors 40 and 41 to
conveyors 42 and 43 and stored temporarily on pans 44 and 45. The
saws are then repositioned again, and the entire cycle repeated
until the entire log has been divided into cants having either two
or four inch thicknesses. As explained above, the center cant will
typically be four inches due to the size of the carriage mechanism
20.
The cants stored on pans 35, 36, 44 and 45 are deposited onto a
conveyor 50 which moves each cant past a second optical scanner 55.
This scanner provides information to a computer which controls the
position of adjustable stops 56 and 57 to orient each cant with
respect to cant chippers 58 and 59. In the embodiment shown, cant
chipper 58 is fixed while chipper 59 is adjustable. These chippers
remove the wane from the cant in such a way as to maximize the
number of studs available therefrom.
The two inch cants are carried by conveyor 61 through a four inch
gang edger 62 which divides the cant into 2 .times. 4's and
deposits them onto an outfeed conveyor 65. The four inch cants are
carried by conveyors 66 and 67 through either a two inch gang edger
68 or the four inch gang edger 62 and then onto the outfeed
conveyor 65.
By using an optical device which measures the volume of each log
entering the mill, and by careful selection of the widths of the
cants into which each log is cut, and the orientation of each cant
with respect to the saws which divide it into studs, the number of
studs available from any given log is increased over that presently
available in manually controlled mills.
The second optical scanner 55 is shown in FIGS. 3-5 with a cant 70
approaching the scanning position. The scanner includes a first
source of light 71 which is so positioned as to direct the light at
a low angle of incidence across a cant 70. Each cant includes a
sawn portion 73 (FIG. 7), a leading wane 74 and a trailing wane 75.
The leading wane 74 is defined as that portion of the cant 70
between the leading edge of the sawn portion 73 and the leading
edge 76 of the cant. Similarly, the trailing wane 75 is defined as
that portion of the cant between the trailing edge of the sawn
portion and the trailing edge 77 of the cant. The first light
source 71 therefore illuminates the sawn portion 73 as well as the
trailing wane 75.
Each cant 70 is carried to the optical scanner by a conveyor 50
which moves the cant at a first rate of speed. Within the area of
the optical scanner 55, however, the cant 70 engages lugs 80 and 81
which are moved by a second conveyor 85. The second conveyor is
moved at a second or slower rate of speed and therefore the
conveyor 50 will force the leading edge 76 of the cant into
positive engagement with the lugs 80. As will be explained, these
lugs provide a reference against which the locations of the leading
and trailing edges of the cant and the leading and trailing edges
of the sawn portion of the cant is measured. In the embodiment
shown in FIG. 4, equally spaced lug pairs 80 are carried by the
conveyor 85. The conveyor 85 is moved at the second rate of speed
by a motor 86 with its speed measured by a shaft encoding device or
tachometer generator 90.
The optical scanner 55 also includes a second light source 91 which
directs light at a low angle of incidence across the cant to
illuminate the sawn portion 73 and the leading wane 74. In the
embodiment shown, a light screen or baffle 95 is provided to
maintain these two light sources separate so that the cant is
illuminated by only one light source at a time. It is also within
the scope of this invention, however, to provide switch means which
will alternately energize the light sources in which case there
would be no need for such a light screen.
A plurality of spaced photodetectors are positioned to sense the
light reflected by the cant from the light sources 71 and 91. This
reflected light provides information on the location of the edges
of the cant as well as the edges of the sawn portion and will
enable appropriate electronic circuitry to determine the maximum
number of studs which may be cut from the cant and to orient the
cant with respect to chippers and saws to yield this result.
In the embodiment shown in FIGS. 3-5, two sets of photodetectors
100 and 105 are employed, each set including 27 individual
photodetectors spaced substantially equally across the cant. The
photodetector set 100 observes the light reflected by the cant from
light source 71 while the photodetector set 105 detects the light
reflected by the cant from light source 91. Located within the
viewing area of each photodetector set are baffles 106 which
function merely to prevent stray light from causing erroneous
readings by the photodetectors. Additional screens 107 are
provided, also to prevent stray light from being directed into the
viewing area and cause erroneous indications.
By combining the outputs from the individual photodetectors of the
sets 100 and 105 with the output of the tachometer 90, a
rectilinear representation of the available wood in the cant may be
generated. Since the leading edge 76 of the cant may not be
reasonably straight, a reference coordinate 110 against which this
information is referenced is established ahead of the cant by
approximately 10 inches and is generated by a detector 115 located
below the conveyor which senses the passage of one of the lugs 80
carried by the conveyor 85. Of course, other means for establishing
a reference may be employed, such as a photodetector sensing the
passage of a cant just prior to its moving into the viewing
area.
Referring now to FIGS. 6 and 7, a cant 70 is moved by the conveyor
85 past the first set of photodetectors 100 and since the sawn
portion 73 and the trailing wane 75 are illuminated by light from
the source 71, both of these surfaces will reflect light into the
photodetectors. Therefore, each photodetector output will show an
increase of light at the beginning of the sawn portion and will not
show a significant decrease in the level of illumination until
after the trailing edge 77 of the cant passes. A photodetector
output is shown by waveform 120 with an increase in light intensity
representing the leading edge of the sawn portion occurring at Y1
and a decrease in light intensity, representing the trailing edge
of the cant occurring at Y3.
As the cant 70 moves past the photodetector set 105, a second
output waveform 125 will be developed. Since the cant is now
illuminated by the light source 91, the sawn portion 73 and the
leading wane 74 are illuminated and therefore the photodetector
will sense light at the leading edge of the cant, identified in the
waveform at Y0, and the light intensity will fall off at the
trailing edge of the sawn portion, identified at Y2, since the
trailing wane 75 will be in shadow.
In FIG. 7, the distances Y0, Y1, Y2 and Y3 are shown measured from
the reference 110 which is established when one of the lugs 80
passes the detector 115. Although not shown in FIG. 7, it is
understood that these "Y" distances are established for each of
twenty-seven positions across the cant.
As mentioned previously, it is within the scope of the invention to
provide a single set of photodetectors and to provide two light
sources with means to switch alternately between the sources, thus
eliminating the need for a light screen.
Referring to FIG. 8, a set of photodetectors 130 are positioned on
a line extending transversely across the conveyor system 55. A
first light source 131 is positioned to the right, as viewed in
FIG. 8, to direct light at a low angle of incidence across the cant
70 to illuminate the sawn portion 73 and the trailing wane 75.
Similarly, a second light source 132 is positioned at the left in
FIG. 8, to direct light at a low angle of incidence across the cant
to illuminate the sawn portion 73 and the leading wane 74.
Each light source 116, 117 may include a plurality of light
emitting diodes (LED) arranged with one or more LEDs for each
photodetector position across the cant. The LEDs within each light
source 131 and 132 may be connected in series and driven from a
common power supply. The light sources 131 and 132 may be energized
alternately and the output from the photodetectors 130 sampled
during the period of energization to determine the amount of
reflected light under the direction of a control circuit 135.
Alternately, the light sources 131 and 132 may be switched at the
same repetition rate but out of phase, and the photodetectors
sampled in synchronism with the phase of the light sources. The
switching rate may be governed by the tachometer generator 90 in
accordance with the speed of movement of the cant.
In FIG. 8 where light emitting diodes may be used, they would be
positioned closer to the cant than the steady state quartz-line
lamps 71 and 91 shown in FIG. 3 since the intensity of the light
output from light emitting diodes at present is less than that of
other conventional light sources. A cylindrical lens may be used to
focus the light onto the cant.
Once the grid coordinates of the leading and trailing edges of the
sawn portion and of the cant itself are determined, the cant may be
so positioned so that the leading wane may be removed by a fixed
chipper 58 and the trailing wane removed by an adjustable clipper
59. To orient the wane with respect to the fixed chipper, a pair of
adjustable stops 56 and 57, which are substantially in line with
the lugs 80 and 81, are adjusted by the output of an electronic
circuit 140 (FIG. 3). The adjustable stops 56 and 57 are attached
to and positioned by stacked cylinder devices 141 and 142. These
devices are pneumatically actuated cylinders which move in a
digital manner through preset distances under the control of the
circuit 130. The precision to which these devices may adjust the
stops 56 and 57 depends upon movement of the smallest cylinder
within each stack. Since the adjustable stops 56 and 57 are in line
with the lugs 80, undulations in the leading edge of the cant will
not effect the orientation of the cant with respect to the chipper.
It may be seen in FIG. 4 that the lugs 80 disengage from the cant
after the cant has passed through the scanning area and therefore
the cant will accelerate to the speed of the conveyor 50 until it
engages the adjustable stops 56 and 57.
The position of the adjustable chipper 59 is also determined by the
circuit 140 and will remove all or a substantial part of the
trailing wane 75 after the cant has been transferred from the
conveyor 50 onto the conveyor 61 (FIG. 1). The positioning
mechanism for the adjustable chipper 58 in a preferred embodiment
of the invention is a device manufactured by General Electric under
the trademark Accupin.
It is also possible within the scope of this invention to provide
other means for positioning the cant with respect to the chippers
58 and 59. For example, the lugs 80 could be adjustable
independently of each other in order to position the cant. Also,
while the cant is shown moving transversely through the scanner, it
could also move longitudinally through the scanner with other means
provided to orient the cant with respect to the clippers.
Also located within the scanning area is a sensing device 145 which
determines whether the cants are two or four inches in thickness.
Memory means are provided to follow the cant through the chippers
and to cause the cant to be directed either to the two inch or the
four inch gang edges 62 or 68, depending on the size of studs
required.
While the form of apparatus herein described constitutes a
preferred embodiment of the invention, it is to be understood that
the invention is not limited to this precise form of apparatus, and
that changes may be made therein without departing from the scope
of the invention which is defined in the appended claims.
* * * * *