U.S. patent number 3,885,483 [Application Number 05/406,957] was granted by the patent office on 1975-05-27 for saw apparatus.
This patent grant is currently assigned to Nippon Gakki Seizo Kabushiki Kaisha. Invention is credited to Akira Ikeya, Toshiyuki Suzuki, Hiroshi Ueno.
United States Patent |
3,885,483 |
Ikeya , et al. |
May 27, 1975 |
Saw apparatus
Abstract
Herein disclosed is a saw apparatus having circular saw blades
which are independently axially movable on a rotary shaft
supporting the blades for cutting a board to sections along
markings applied on the face or faces of the board. The markings
are sensed by a scanning arrangement and signals are produced when
the scanning arrangement detects the markings. The saw blades are
shifted to positions specified by these signals which represent the
locations of the individual markings.
Inventors: |
Ikeya; Akira (Hamakita,
JA), Ueno; Hiroshi (Hamakita, JA), Suzuki;
Toshiyuki (Hamakita, JA) |
Assignee: |
Nippon Gakki Seizo Kabushiki
Kaisha (Hamamatsu-shi, JA)
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Family
ID: |
27550101 |
Appl.
No.: |
05/406,957 |
Filed: |
October 16, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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284150 |
Aug 28, 1972 |
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Foreign Application Priority Data
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Aug 17, 1971 [JA] |
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46-77691 |
Aug 27, 1971 [JA] |
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46-77692 |
Aug 27, 1971 [JA] |
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46-66037 |
Aug 27, 1971 [JA] |
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46-66038 |
Aug 27, 1971 [JA] |
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46-66039 |
Apr 29, 1972 [JA] |
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47-43001 |
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Current U.S.
Class: |
83/365; 83/76.1;
83/425.4; 83/368; 144/356 |
Current CPC
Class: |
B27B
1/007 (20130101); B27B 31/06 (20130101); B27B
5/34 (20130101); B27B 31/003 (20130101); B26D
7/2635 (20130101); B27B 5/06 (20130101); B27G
1/00 (20130101); Y10T 83/533 (20150401); B26D
2007/2657 (20130101); Y10T 83/538 (20150401); Y10T
83/659 (20150401); Y10T 83/162 (20150401) |
Current International
Class: |
B27B
1/00 (20060101); B26D 7/26 (20060101); B27B
5/34 (20060101); B27B 31/06 (20060101); B27B
31/00 (20060101); B27B 5/06 (20060101); B27B
5/00 (20060101); B27G 1/00 (20060101); B26d
005/34 (); B27b 007/04 () |
Field of
Search: |
;83/368,425.4,365,157,71
;144/312 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schran; Donald R.
Attorney, Agent or Firm: Berman; Hans
Parent Case Text
This is a continuation of application Ser. No. 284,150, filed Aug.
28, 1972, and now abandoned.
Claims
What is claimed is:
1. A saw apparatus for cutting a board into sections in accordance
with at least one marking applied thereto, comprising at least one
blade conveying means for conveying the marked board in a
predetermined path which is aligned with said at least one saw
blade, scanning means operable to detect said at least one marking
on the board, signal generating means responsive to said scanning
means for producing a signal representative of the location of said
at least one marking, and saw-blade shifting means responsive to
said signal for axially moving said at least one saw blade to a
position aligned with said marking.
2. A saw apparatus as set forth in claim 1, in which said scanning
means comprises a carrier which is movable over said path for
scanning the marked board, a source of light for irradiating said
marked board and a plurality of photo-electric elements operable to
produce a signal voltage upon sensing said at least one marking on
the board.
3. A saw apparatus as set forth in claim 1, in which said signal
generating means comprises mark-position indicating signal
generating means responsive to said scanning means, a
blade-position indicating signal generating means responsive to
said saw-blade shifting means and comparing means for comparing the
signals from said mark-position and blade position indicating
signal generating means and producing a control signal for causing
said saw-blade shifting means to move said at least one saw blade
to a position in which said signals are equalized.
4. A saw apparatus as set forth in claim 2, in which said signal
generating means comprises gearing means movable responsive to the
movement of said carrier, at least one mark-position indicating
potentiometer responsive to the motion of the bearing means for
producing a signal voltage proportional to the distance of movement
of said carrier over said path, means for disconnecting said
potentiometer from said gearing means when said at least one
marking on the board is detected by said scanning means, at least
one blade-position indicating potentiometer responsive to the axial
movement of said at least one saw blade on said rotary shaft for
producing a signal voltage indicative of the position of the saw
blade on the shaft, and comparing means for comparing the signal
voltages from said mark-position and blade-position indicating
potentiometers and producing a control signal for causing said
saw-blade shifting means to move said at least one saw blade to a
position in which said signals from said mark-position and
blade-position indicating potentiometers are equal to each
other.
5. A saw apparatus as set forth in claim 1, in which said conveying
means comprises a conveyor traveling below said at least one saw
blade in a direction transverse to said rotary shaft, and pressing
means positioned adjacent said conveyor and said at least one saw
blade for pressing the board to be cut and cut sections of the
board upon said conveyor.
6. A saw apparatus as set forth in claim 5, in which said pressing
means comprises a plurality of rollers positioned ahead of and
behind said at least one saw blade in said path and spring means
biasing said rollers toward said conveyor.
7. A saw apparatus as set forth in claim 6, wherein the rollers
positioned behind said at least one saw blade include a first set
of rollers and a second set of rollers, the rollers of each set
being mounted for rotation about respective parallel axes
transverse to said path in axially spaced relationship, the two
axially terminal portions of a roller in each set being axially
coextensive with respective axially terminal portions of two
rollers in the other set.
8. A saw apparatus as set forth in claim 6, in which said conveying
means further comprises return-preventive means positioned ahead of
said at least one saw blade for preventing rearward movement of the
board conveyed to said saw blade.
9. A saw apparatus as set forth in claim 1, in which said saw-blade
shifting means includes saw-blade guiding means for guiding said at
least one saw blade on said rotary shaft when said saw blade is
moved axially thereon.
10. A saw apparatus as set forth in claim 1, further comprising
saw-blade position indicating means cooperating with said saw-blade
shifting means for visually indicating the axial position of said
at least one saw blade.
11. A saw apparatus as set forth in claim 1, in which said scanning
means includes stop means for temporarily holding said marked board
at a standstill adjacent said scanning means when the scanning
means is operative to scan the board.
12. A saw apparatus for cutting a board into sections in accordance
with at least one marking applied thereto, comprising at least one
movable saw blade, conveying means for conveying the marked board
in a predetermined path, scanning means operable to detect said at
least one marking on the board, signal generating means responsive
to said scanning means for producing a signal representative of the
location of said at least one marking, and saw-blade shifting means
responsive to said signal for moving said at least one saw blade to
a position which is substantially aligned with said marking in said
path for cutting engagement with the conveyed board.
13. A saw apparatus for cutting a board into sections in accordance
with at least one marking applied thereto, comprising at least one
saw blade movable between a plurality of positions, first signal
generating means for producing a first signal representative of the
location of said at least one marking on the board, second signal
generating means for producing a second signal representative of
the instantaneous position of said saw blade, comparing means for
comparing said first and second signals and for producing a third
signal which is representative of the distance between said
location of the marking and said instantaneous position of the saw
blade, and saw-blade shifting means responsive to said third signal
for moving said saw blade from said instantaneous position toward
another position thereof nearer said marking.
14. A saw apparatus for cutting a board into sections comprising a
shaft having an axis and mounted for rotation about said axis; at
least one circular saw blade mounted on said shaft for rotation
therewith and for axial movement relative to said shaft; conveying
means for conveying said board past said blade in a path transverse
to said axis, said conveying means including a conveyor traveling
below said shaft for cutting of a board carried by said conveyor
into a plurality of sections by said at least one saw blade, and
pressing means spacedly above said conveyor and adjacent said at
least one saw blade for pressing said sections downwardly upon said
conveyor, said pressing means including a plurality of first sets
of rollers, a plurality of second sets of rollers, the rollers of
each set being mounted for rotation about respective parallel axes
transverse to said path in axially spaced relationship, the two
axially terminal portions of a roller in each first set being
axially coextensive with respective axially terminal portions of
two rollers in an adjacent one of said second sets, and spring
means biasing said rollers toward said conveyor.
Description
The present invention relates to saw apparatus for use in lumber
mill operations and, more particularly, to a saw apparatus having
at least one circular saw blade which is axially movable on an
arbor on which the saw blade is mounted.
While the saw apparatus herein disclosed may be of any of the types
such as ripsaws, crosscut saws and miters, the present invention
will be described as embodied, by way of example, in ripsaw
machines for cutting planks, boards or slabs, especially boards
having knots or flaws.
For the purpose of preparing boards which are clear of knots or
flaws, it is presently an ordinary practice that an operator marks
the supplied board in volatile ink for identification of the
objectionable knots or flaws and another operator then feeds the
board to the ripsaw machine upon visual inspection of the marks to
cut off the marked sections. Since, the board usually has two or
more knots or flaws and is thus marked at two or more spots, it is
necessary to have the board or cut section or sections of the board
fed to the saw a number of times until all the knots are removed
therefrom. The cut section or sections of the board must therefore
be returned from the delivery side of the saw by a third operator
usually by the use of a conveyor arrangement. At least three
operators are thus required for the preparation of knotless or
flawless boards in the lumber mill, resulting in unsatisfactory
operation efficiency.
A ripsaw machine has therefore been proposed and put in practical
use in which a plurality of saw blades are axially movable on an
arbor positioned transversely to the direction of travel of the
board. The saw blades are moved to align with the markings on the
board to be cut so that the board is cut into sections all at a
time along the markings. At least two operators are required to
carry out this operation, one for marking the board and the other
for feeding the board to the saw and positioning the saw blades in
accordance with the given markings on the board. The operation
efficiency is thus still unsatisfactory. Since, moreover, the saw
blades are shifted by the use of a pushbutton arrangement,
meticulous and time-consuming manipulation of the pushbuttom
arrangement is indispensable for having the saw blades accurately
positioned in compliance with the markings on the board.
It is, therefore, an important object of the present invention to
provide an improved saw apparatus which is capable of preparing
knotless or flawless boards at a satisfactorily enhanced operation
efficiency.
It is another important object of the invention to provide an
improved saw apparatus which is capable of cutting a board into two
or more knotless or flawless sections in a completely automatized
fashion in accordance with the markings preliminarily applied to
the board for identification of the knots or flaws.
It is still another important object of the invention to provide an
improved saw apparatus adapted to automatically cut a board to
sections with utmost accuracy in accordance with the markings on
the board.
The object of the present invention will be advantageously
accomplished in a saw apparatus which comprises a rotary shaft, at
least one circular saw blade which is rotatable with and axially
movable on the rotary shaft, conveying means for conveying the
marked board in a predetermined path which is aligned with the saw
blade or blades, light-sensitive scanning means operable for
detecting the marking or markings on the board, signal generating
means responsive to the scanning means for producing a signal
representative of the location of each marking on the board, and
saw-blade positioning or shifting means responsive to the signal or
signals from the signal generating means for moving the saw blade
or blades to a position or positions which are aligned respectively
with the marking or markings whereby the board is cut into sections
along the marking or markings. The conveying means may comprise
board guiding means for guiding the board in the predetermined path
which is transverse to the rotary shaft when the board is being
passed through the light-sensitive scanning means and through the
saw blade or blades. The conveying means may further comprise stop
means associated with the light-sensitive scanning means for
temporarily holding the board at a standstill when the board is
being scanned by the scanning means. The saw-blade shifting means
usually comprises driving means which is normally operative,
control means responsive to the signal or signals from the signal
generating means for actuating the drive means, and transmitting
means for transmitting mechanical power from the driving means to
the saw blade or blades. The light-sensitive scanning means may be
constructed in any desired manner but, in the preferred embodiment
which is to be described, such means is adapted to be moved
relative to the board and to respond to the marking or markings on
the board. Thus, the light-sensitive scanning means may comprise a
carrier which is movable over the path of the board in a direction
transverse thereto, a source of light to irradiate the board to be
scanned, a plurality of photoelectric elements stationary on the
carrier, driving means for moving the carrier in the aforesaid
direction, and switching means for controlling the movement of the
carrier relative to the board. Where the light-sensitive scanning
means is constructed in this manner, the signal generating means
may comprise gearing means responsive to the movement of the
carrier of the scanning means, at least one mark-position
indicative potentiometer responsive to the motion of the gearing
means for producing a signal voltage which is indicative of the
location of each marking on the board, uncoupling means for
disconnecting the potentiometer from the gearing means when the
marking on the board is detected by the light-sensitive scanning
means, at least one blade-position indicative potentiometer
responsive to the axial movement of the associated saw blade for
producing a signal voltage indicative of the instantaneous position
of the saw blade on the rotary shaft, and comparing means for
comparing the signal voltages from the mark-position and
blade-position indicative potentiometers for producing an output
voltage which is proportional to the difference between the signal
voltages from the potentiometers. In this instance, the control
means of the saw-blade shifting means may comprise valve means
which is responsive to the output signal from the comparing means
of the signal generating means so that the associated saw blade is
moved in a manner to reduce or increase the signal voltage from the
bladeposition indicative potentiometer and accordingly vary the
output voltage from the comparing means to zero.
The conveying means includes a conveyor such as a caterpillar
conveyor which is positioned in association with the saw blade or
blades so that the board is conveyed thereon in a direction
transverse to the rotary shaft carrying the saw blade or blades. It
is, in this instance, preferably that the conveying means further
includes elastic pressing means adapted to elastically press the
board or the cut sections of the board upon the conveyor and to
accordingly enable the board or cut sections to advance in a
stabilized condition while the board is being fed to the saw blade
or blades or the cut sections of the board are leaving the saw
blade or blades. The individual cut sections of the board usually
have reduced widths and, as a consequence, a difficulty may be
encountered in stably retaining the cut sections between the
pressing means and the conveyor especially where the supplied board
has a thickness varying widthwise of the board. This difficuty will
be eliminated through provision of first and second sets of rollers
which are positioned anterior and parallel to the rotary shaft
mounting the saw blade or blades and a plurality of spring means
which are operable to respectively press the rollers against the
individual cut sections of the board which are being conveyed away
from the saw blade or blades. The rollers of each set are aligned
with and axially spaced from each other and, furthermore, the first
and second sets of rollers are disposed alternately from each other
and partly coextensively at their axial end portions.
To prevent the board from being moved backwardly from the saw or
blade or blades by the rotary action of the blade or blades,
return-preventive means in a suitable form may be positioned
anterior to the saw blade or blades and in association with the
pressing means. The position of the pressing means relative to the
conveyor underlying the saw blade or blades may be adjusted to meet
the thickness of the board through provision of suitable adjusting
means.
The saw blade or blades are usually encased in a suitable housing
and, thus, it is difficult, if not impossible, visually to inspect
the saw blade or blades from the outside of the apparatus during
operation. To enable the operator (or the marker) to visually
confirm the movement of the saw blade or blades, there may be
provided saw-blade position indicating means which cooperate with
the saw-blade shifting means.
The saw apparatus having the general construction above described
may further comprise preliminary conveying means which is adapted
to completely automatize the sawing operation using the saw
apparatus. The preliminary conveying means is associated with the
main conveying means and is thus operable to supply the marked
boards to a starting end of the main conveying means from the
marking station. In one preferred form, the preliminary conveying
means comprises a conveyor adapted to move the marked board in a
direction substantially transverse to the path of the board to be
carried on the main conveying means, stopping means for stopping
the preliminary conveying means when the board carried thereon is
brought into alignment with the direction of movement of the main
conveying means, and transfer means for passing the board from the
preliminary to the main conveying means when the preliminary
conveying means is stopped.
The features and advantages of the saw apparatus according to the
present invention will become more apparent from the following
description taken in conjunction with the accompanying drawings, in
which:
FIG. 1 is a plan view showing an overall construction of the saw
apparatus embodying the present invention;
FIG. 2 is a longitudinal sectional view showing in a schematic form
the saw-blade shifting meachanism of the saw apparatus illustrated
in FIG. 1;
FIG. 3 is a cross sectional view showing on an enlarged scale the
saw-blade guiding arrangement of the shifting mechanism illustrated
in FIG. 2;
FIG. 4 is a perspective view showing a shifter forming part of the
shifting mechanism of FIG. 2;
FIG. 5 is an end view showing relative positions of some essential
parts and elements of the shifting mechanism;
FIG. 6a is a cut-away view showing partly in vertical section the
board feeding and delivery mechanisms for the circular saw unit of
the apparatus according to the present invention;
FIG. 6b is also a cut-away view showing, now partly in horizontal
section, the feeding and delivery mechanisms of FIG. 6a;
FIG. 7a is a schematic plan view of the blade-position indicating
arrangement of the saw apparatus shown in FIG. 1;
FIG. 7b is a front end view of an indicator panel forming part of
the blade-position indicating arrangement of FIG. 7a;
FIG. 8 is a plan view showing, on an enlarged scale, a modified
form of light-sensitive scanning and signal generating arrangements
to be incorporated in the saw apparatus according to the present
invention;
FIG. 9a is a schematic circuit diagram of a preferred example of
the signal generating arrangement of the saw apparatus; and
FIG. 9b is a schematic view showing part of the signal generating
arrangement and the control arrangement of the blade shifting
mechanism of the saw apparatus of the present invention.
Reference will now be made to the drawings, first to FIG. 1 in
which the overall construction of the saw apparatus in a preferred
form is illustrated.
As previously discussed, the saw apparatus herein proposed is
specifically adapted to cut wood boards into sections which are
cleared of knots or flaws in a completely automatized fashion and
with utmost accuracy. The boards, designated by reference numeral
10, are thus successively supplied from a board marking station
(not shown) at which markings m are applied to the boards to
identify the locations of the knots or flaws k, if any, on the
boards. A suitable preliminary conveying arrangement 12 is adapted
to pass the marked boards 10 to a light-sensitive scanning and
signal generating arrangement 14 which detects and memorizes the
locations of the markings m on the boards 10. The boards 10 are
then fed through an intermediate transfer mechanism 16 to a sawing
unit 18 which is positioned over a board feeding and delivery
arrangement 20. The sawing unit 18 is associated with a saw-blade
positioning or shifting mechanism 22 which is operable to move the
saw blades of the unit in accordance with the signals from the
scanning and signal generating arrangement 14. A blade-position
indicating arrangement 24 cooperates with the blade shifting
mechanism so as to visually indicate the positions of the saw
blades for permitting the operator to monitor the operation of the
sawing unit 18.
The preliminary conveying arrangement 12 includes an endless belt
conveyor 26 which is driven to move the marked boards 10 in a
predetermined direction which is usually transverse to the path of
the boards to the sawing unit 18. A rail 28 serving as a stop
member is positioned transversely to the direction of travel of the
belt conveyor 26 and carries thereon a limit switch 30 which is
adapted to be actuated when the board 10 strikes against the stop
member 28 and is thus brought to a standstill on the conveyor 26. A
pneumatic of hydraulic cylinder 32 has a plunger 32a which is
extendible across the entire width of the belt 26. Both the
conveyor 26 and cylinder 32 coact with the limit switch 30 so that,
when the limit switch is actuated, the conveyor 26 stops and the
plunger 32a of the cylinder 32 is extended from its retracted
position whereby the board 10 bearing against the stop member 28 is
passed over to the succeeding station. The plunger 32a of the
cylinder 32 is then withdrawn to its initial position until it
presses a limit switch 34 which is carried on the cylinder 32.
The board 10 which has thus left the conveyor 26 is now moved on a
main conveying mechanism including a conveyor 36 and an associated
guide rail 38. The conveyor 36 and guide rail 38 are adapted to
guide the board 10 in a direction which is transverse to the
direction of travel of the preliminary conveyor 26 and to the axis
of rotation of the saw blades of the sawing unit 18 to be descried
later. The guide rail 38 is integral with the stop member 28 of the
preceding conveying station. A pressing rod 40 is biased by a
spring to rotate about its pivot toward the guide rail 38 and thus
presses the board 10 against the guide rail 38 when the board
passes between the rail 38 and pressing rod 40, as illustrated.
The conveyor 36 may be positively driven from a suitable driving
source or, where desired, may not be driven positively. If, thus,
the conveyor 36 is not positively driven, then an arrangement may
be provided so that the board 10 carried on the conveyor is moved
foreward by means of a succeeding board which is moved from the
preliminary conveyor 26 by the plunger 32a of the pneumatic or
hydraulic cylinder 32. Where, moreover, it is desired that the
board 10 be marked on both sides thereof, the conveyor 36 may be
constituted as a roller conveyor as illustrated so that the
markings on both faces of the board can be detected.
At the forward end of the conveyor 36 are positioned gate members
42 and 42' which are adapted to be raised and lowered through the
upper level of the conveyor 36 by suitable driving means (not
shown). When, thus, the gate members 42 and 42' are in the raised
positions, the board 10 bears at its forward end against these
members and is consequently held at a standstill on the conveyor 36
as illustrated. The gate members 42 and 42' are controlled by the
previously mentioned limit switch 30 and are thus raised when the
switch 30 is actuated and accordingly the board 10 is transferred
from the preliminary conveyor 26 to the main conveyor 36.
When the board 10 is thus held at rest on the conveyor 36, then the
light-sensitive scanning and signal generating arrangement 12 is
initiated into action so as to produce signals representative of
the locations of the markings m on the board. The scanning and
signal generating arrangement 14 is controlled by a limit switch 44
which is located at the forward end of the conveyor 36. The limit
switch 44 is adapted to be actuated when pressed upon by the board
10 reaching the forward end of the conveyor 36 and thus held at a
standstill by the gate members 42 and 42'. This limit switch 44 is
also associated with the cylinder 32 of the preliminary conveying
arrangement 12 so that the plunger 32a of the cylinder 32 is
withdrawn from its fully projecting position when the limit switch
44 is actuated.
The light-sensitive scanning and signal generating arrangement 14
includes a carrier 46 which carries thereon a plurality of lights
46a and a plurality of photo-electric elements 46b which are
uniformly spaced from each other. The photo-electric elements 46a
per se are well known in the art, producing signal voltages which
are proportional to the intensities of the light incident thereon
from the surface of the board 10 which is irradiated with the light
from the light sources 46a. The carrier 46 is mounted on spaced
guide bars 48 and 48' having rollers 50 and 52', respectively, and
is thus movable transversely to the direction of travel of the
board 10, viz., to the guide rail 38, across the conveyor 36. The
carrier is driven by suitable driving means such as for example a
pneumatic or hydraulic cylinder 52 having a piston which extends
transversely to the carrier 46. This piston of the cylinder 52 is
integral with or rigidly connected to a toothed bar or rack 54
which forms part of a mark-position signal generator. The
mark-position signal generator, generally designated by reference
numeral 56, includes a support 58 carrying thereon a desired number
of pinions 60 which are in mesh with the bar 54. The number of the
pinions 60 is equal to the number of the cutting elements of the
sawing unit 18. The sawing unit 18 is herein assumed by way of
example to have four saw blades as will be described later and four
pinions 60 are used in the embodiment illustrated. The pinions 60
are respectively connected with potentiometers 62 through shafts
64. These potentiometers 62 produce voltages proportional to the
angles of rotation of the pinions 60 on the bar 54 and are
disconnected by suitable uncoupling means such as clutches 66
positioned intermediate the pinions 60 and potentiometers 62 when
associated photo-electric elements 46b on the carrier 46 detect the
markings m on the board 10, as will be described in more detail.
The clutches 66 are preferably provided with brakes (not shown)
which are adapted to positively stop the rotation of the associated
potentiometers 62 when the potentiometers are uncoupled from the
pinions 60. The clutches and the associated brakes are usually of
the solenoid actuated types. Designated by reference numeral 68 are
torque limiters which are preferably connected between the pinions
60 and clutches 66.
Limit switches 70 and 72 are positioned at the ends of the path of
the carrier 46. The limit switch 70 remote from the guide rail 38
is actuated to return the carrier 46 to the initial position close
to the guide rail 38 when engaged by the carrier 46. This limit
switch 70 is further operable to lower the gate members 42 and 42'
and to uncouple the clutch or clutches 66 which are kept coupled
when the carrier 46 reaches the position farthest from the initial
or rest position. The limit switch 72, on the other hand, is
responsive to the return of the carrier 46 and holds it in the rest
or inoperative position until the limit switch 44 is actuated for a
second time.
While the carrier 46 is thus moved across the board 10 resting on
the conveyor 36, the photo-electric elements 46b sense the markings
m on the board 10 so that the potentiometers 62 produce signals
representative of the locations of the markings. Upon completion of
the scanning operation, the limit switch 70 is actuated and
accordingly the gate members 42 and 42' are lowered, thereby
permitting the board 10 on the conveyor 36 to be advanced by the
positively driven conveyor 36 or by the succeeding board being
moved from the preliminary conveyor 26. The board 10 is thus passed
to the intermediate transfer mechanism 16.
The intermediate transfer mechanism 16 forms part of the main
conveying arrangement and includes a plurality of spaced rollers 74
which are driven by a driving motor 76 through a reduction gearing
78 and a coupling 80 as is customary. The transfer mechanism 16 in
its entirety may be preferably to positioned as to have the board
10 constantly pressed upon the guide rail 38. The board 10 leaving
the transfer mechanism 16 is now conveyed on a suitable type of
conveyor such as a caterpillar conveyor 82 which also forms part of
the main conveying arrangement of the saw apparatus according to
the present invention. The conveyor 82 is driven by a driving motor
84 through non-illustrated reduction gearing for feeding the board
10 to the sawing unit 18. Designated by reference numeral 86 is a
lubricating arrangement for the conveyor.
The board 10 thus fed to the sawing unit 18 is cut into sections by
blades which are moved to positions selected in accordance with the
signals from the potentiometers 62 of the mark-position signal
generator 56. To prevent the saw blades of the unit 18 from being
shifted during the cutting operation, sensors 88 and 88' and 90 and
90' may preferably be provided which are responsive to the presence
and absence of the board on the sawing unit. Such sensors may be of
the type using photo-electric elements.
The sawing unit 18 and the associated saw-blade shifting mechanism
22 are illustrated in FIGS. 2 and 3. As seen in FIG. 2, the sawing
unit is carried on a rotary shaft 92 which is rotatable on a casing
94 in bearings 96, 98 and 100. The rotary shaft 92 is driven by a
grooved pulley 102 and beltings 104. A pair of outer collars 106a
and 106d and a pair of inner collars 106b and 106c are axially
moved on the shaft 92 by guiding means which are to be described
later. The outer collars 106a and 106d have flange portions
extending toward each other and spaced from the rotary shaft 92.
The flange portions of the outer collars 106a and 106d have inner
peripheral surfaces engageable with outer peripheral surfaces of
inner collars 106b and 106c, respectively. Likewise, the inner
collars 106b and 106c have flanges or annular projections which are
engageable with the leading ends of the cylindrical flanges of the
outer collars 106a and 106d, respectively. The collars 106a to 106d
carry on their flange portions circular saw blades 108a to 108d,
respectively, which are thus movable with the associated collars in
an axial direction on the shaft 92 and independently of each other.
Four saw blades 108a to 108d are herein shown by way of example. It
is, however, apparent that the number of the saw blades can be
increased or decreased as desired depending upon requirements. The
collars 106a to 106d are splined or keyed as at 110 in FIG. 3 to
the shaft 92 so as to rotate therewith when the shaft is
driven.
The rotary shaft 92 is formed with at least four circumferentially
spaced grooves 112 having enlarged bottoms as seen in FIG. 3 and
axially extending from one end of the shaft 92 to the other. Guide
rods 114 are conformingly received in of the grooves 112,
longitudinally slidable in these grooves and secured respectively
at one end to the collars 106a to 106d through a pin or pins 116,
as seen in FIG. 3. Designated by reference numeral 118 are
retainers for holding the pin or pins 116 in position.
Each of the guide rods 114 is connected at the other end to a
sleeve 120 which is axially slidable on the rotary shaft 92 out of
range of the conveyor 82, as seen in FIG. 2. A ring 124 having an
annular extension 124a is rotatable on this sleeve 120 through a
bearing 126, the ring 124 being prevented from moving axially on
the sleeve 120. This ring 124 is moved by means of a shifter 128
which is slidable on a guide shaft 130 parallel to the rotary shaft
92 and supported on the casing 94. The construction of the shifter
128 is more clearly seen in FIG. 4. Referring thus to FIG. 4, the
shifter 128 has a sleeve portion 132 which is axially slidable on
the guide shaft 130 and a fork or a pair of lower arms 134 and 134'
which override the ring 124 (FIG. 2). The spaced lower arms 134 and
134' have lower ends portions 136 and 136', respectively, which are
in engagement with the annular extension 124a of the ring 124.
These portions 136 and 136' are herein illustrated as constituted
by claws which have notches 138 and 138' adapted to grasp the
annular extension 124a of the ring 124. These claws may be formed
integrally with the arm portions 134 and 134' or may be bolted or
welded thereto where desired. The shifter 128 further includes an
upper projection 140 which is substantially diametrically opposed
to the lower arm portions 134 and 134'. This upper projection 140
is connected to a piston rod 142 of a hydraulic cylinder 144
through an adjustable and cushioning joint 148. The hydraulic
cylinder 144 communicates with a source of a pressurized fluid
through a suitable solenoid operated valve 146 which is controlled
in a manner to be described later.
The sleeve 120, ring 124, shifter 128 and cylinder 144 are provided
on each of the guide rods 114 and accordingly on each of the saw
blades 108a to 108d and, thus, the four independent mechanical
linkages interconnecting the collars 106a to 106d and the four
cylinders 144 constitute the saw-blade shifting mechanism of the
saw apparatus according to the present invention. More
particularly, the sleeves 124 and associated rings 124 are
positioned in series with each other on the rotary shaft 92 while
the shifters 128, guide shafts 130 and cylinders 144 are disposed
substantially concentrically with respect to the rotary shaft 92 as
will be understood from FIG. 5 in which the positions of the guide
shafts now designated by 130a to 130d and cylinders now designated
by 144a to 144d relative to the saw blades commonly designated by
108 are illustrated.
The saw-blade shifting mechanism of the construction above
described is operatively associated with the signal generating
arrangement for controlling the blade shifting operation of the
shifting mechanism in accordance with the signal or signals
indicative of the location or locations of the markings on the
board to be cut as previously mentioned. Thus, in the embodiment
shown, a toothed rack 150 is connected at one end to the upper
projection 140 of each of the shifters 128, extending substantially
in parallel to the shafts 92 and 130 an longitudinally movably
supported on the casing 94 as seen in FIG. 2. The rack 150 is in
constant mesh with a pinion 152 which is rotatable on a shaft 154
carried on the casing 94 through a bracket 156 positioned
externally of the casing. This shaft 154 is rotatable with a
blade-position indicating potentiometer 158 which is adapted to
produce a signal voltage proportional to the angle of rotation of
the pinion 152 on the rack 150. A rack 150, pinion 152, shaft 154
and potentiometer 158 are associated with each of the shifters 128
and saw blades 108 and angularly offset with respect to the rotary
shaft 92. This will be clearly seen in FIG. 5, in which the
relative positions with respect of the saw blades 108 of the racks,
pinions, shafts and potentiometers all designated with numerals
with subscripts a, b, c and d to correspond to the associated guide
shafts 130a, 130b, 130c and 130d, respectively, are
illustrated.
As illustrated in block form in FIG. 2, the mark-position
indicating potentiometer 62 and the blade-position indicating
potentiometer 158 for each of the saw blades are connected in
parallel to a comparator 160 for controlling the solenoid operated
valve 146 as will be described in more detail. The mark-position
indicating potentiometer produces a signal voltage which is
proportional to the distance of the marking m on the board 10 from
the edge of the board close to the rest position of the carrier 46
of the light-sensitive scanning mechanism (see FIG. 1). The
potentiometer 158 is adapted to produce a signal voltage which is
proportional to the distance of the associated saw blade from the
resting position thereof. These signal voltages are fed to the
comparator 160 the saw blade is moved until the difference between
the voltages from the potentiometers 62 and 158 becomes zero.
FIGS. 6a and 6b illustrate a preferred construction of the board
feeding arrangement 22 which largely consists of a mechanism 22a
for feeding the board 10 to the sawing unit and a mechanism 22b for
delivering the cut sections 10a, 10b, 10c (FIG. 1) of the board 10
from the sawing unit. The board feeding and delivery mechanisms 22a
and 22b, respectively, are accommodated within a casing 162 which
includes reinforcement plates 162a and 162b. The board feeding
mechanism 22a is positioned anterior to the sawing unit having saw
blades 108 and serves to press the board 10 against the conveyor 82
while the board is advancing toward the saw blades 108.
The board feeding mechanism 22a starts with a return-preventive
member 164 which is swingable over the conveyor 82. The
return-preventive member 164 is attached to a pivotal member 166
which is journaled on the casing 162 and biased to turn in a
direction to press the return-preventive member 164 against the
board 10 being passed thereunder. The pivotal member 166 is biased
by a helical spring 170 which is anchored to the rear end portion
of the casing 162. The pivotal member 166 carries thereon an
abutment 172 which is engageable with a stop member 174 projecting
rearwardly of the casing 162 in alignment with the abutment 172.
The pivotal motion of the return-preventive member 164 on the
pivotal member 166 is thus limited by abutting engagement of the
abutment 172 with the stop member 174 so that rearward movement of
the board 10 past the return-preventive member 164 is prevented. A
cross shaft 176 is positioned anterior to or ahead of the sawing
unit and parallel to the rotary shaft carrying the saw blades 108.
The shaft 176 is supported at its opposite ends on the casing 162
as seen in FIG. 6b. Arms 178 and 180 are pivotally mounted on this
cross shaft 176, respectively extending rearwardly and forwardly of
the shaft 176. At the free end portions of these arms 178 and 180
are mounted main pressing rollers 182 and 184 on shafts 182a and
184a, respectively, which are parallel to the cross shaft 176 and
movable relative to the casing 162. The pressing rollers 182 and
184 are thus not only rotatable about the shafts 182a and 184a but
are turnable about the cross shaft 176 on the arms 178 and 180,
respectively. The rearward pressing roller 182 is biased downward
by means of helical compression springs 186 which are seated at
their lower ends on pressing plates 188 resting on the top of the
roller 182 and at their upper ends on spring seat plates 190
supported by adjusting bolts 192 which are fastened to the top wall
of the casing 162 by nuts 194. Likewise, the forward roller 184 is
urged downward by compression springs 196 which are seated between
pressing plates 198 and spring seat plates 200. These spring seat
plates 200 are also secured to adjusting bolts 202 fastened to the
casing 162 by nuts 204. Designated by reference numerals 206 and
208 are stop members for the arms 178 and 180 which are rockable
about and on both sides of the cross shaft 176.
Between the forward pressing roller 184 and the sawing unit is
positioned another cross shaft 210 parallel to the first cross
shaft 176 and supported on the side walls of the casing 162. The
cross shaft 210 carries an arm 212 for an auxiliary pressing roller
214 which is positioned adjacent the sawing unit as seen in FIGS.
6a and 6b. The cross shaft 210 also carries a generally upwardly
extending arm 216 which moves together with the arm 212 about the
shaft 210. The upright arm 216 has mounted at its uppermost portion
a pivotal shaft 218 on which one end of an adjusting rod 220 is
journaled. The adjusting rod 220 extends over the main pressing
rollers 182 and 184 rearwardly of the arm 216 and projects
outwardly of the rear end wall of the casing 162. The adjusting rod
220 is biased forwardly by means of a compression spring 222 which
is seated at its forward end on a spring seat member 224 secured to
the rod 220 and at its rearward end on the rear end wall of the
casing 162. Where desired, the adjusting rod 220 may be screwed at
its outer end portion to an adjusting nut 226 so that the length of
the adjusting rod 220 extending within the casing 162 may be
varied. The cross shaft 210 is further provided with a
return-preventive member 228 which pivots on the shaft 210 in the
direction of the path of the board 10 to be conveyed thereunder.
The return-preventive member 228 has a lower portion directed
generally dowwardly for contact with the board 10 and an upper
portion which is directed generally upwardly and rearwardly. This
upper portion of the return-preventive member 228 is engageable at
its free end with a stop member 230 which is fast on the casing
162. The return-preventive member 228 permits movement of the board
10 on the conveyor 82 toward the sawing unit but prevents the board
from being moved rearwardly, similarly to the return-preventive
member 164 located upstream thereof.
The delivery mechanism 22b, on the other hand, is positioned after
or behind the sawing unit and thus serves to feed the cut sections
of the board to a storage station (not shown) succeeding the saw
apparatus. The delivery mechanism 22b includes a cross shaft 232
parallel to the rotary shaft for the saw blades 108 and supported
on the side walls of the casing 162. The cross shaft 232 carries
thereon a first set of arms 234 and a second set of arms 236. The
arms 234 and 236 of the two sets are juxtaposed alternately and
extend rearwardly from the cross shaft 232 toward the saw blades
108. The arms 234 are shorter than the arms 236. The arms 234 and
236 carry on their downwardly bent end portions pressing rollers
238 and 240 respectively which press upon and roll on the cut
sections of the board on the conveyor 82. The rollers 238 have a
common axis and are axially spaced from each other. Likewise, the
rollers 240 are axially spaced from each other and have a common
axis which is parallel to the axis of the first set of pressing
rollers 238 and accordingly to the cross shaft 232. The pressing
rollers 238 have end portions coextensive with the end portions of
the pressing rollers 240 so that the roller arrangement in its
entirety extends over the entire width of the conveyor 82. The
cross shaft 232 further carries a plurality of generally upwardly
extending arms 242 which are integral with respective arms 234 and
236. These upright arms 242 have pivot pins 244 at their uppermost
portions, and adjusting rods 246 are connected by the pins to the
arms 242. The adjusting rods 246 are biased rearwardly by means of
compression springs 248 which are seated on spring seat members
250, as seen in FIG. 6b. The adjusting rods 246 project beyond the
forward wall of the casing 162 and are provided with adjusting nuts
252 which are connected to the threaded outer end portions of the
rods 246.
Behind the cross shaft 232 is positioned a pressing roller
arrangement which is similar to the roller arrangement of the board
feeding mechanism 22a. The pressing roller arrangement of the
delivery side thus includes a cross shaft 254 supported on the side
walls of the casing 162. The cross shaft 254 pivotally carries at
its opposite end portions rearwardly and forwardly extending arms
256 and 258, respectively. The arms 256 and 258 carry at their free
end portions pressing rollers 260 and 262, respectively. These
pressing rollers 260 and 262 are urged downward by spring means
which are carried on the top wall of the casing though not shown so
that the rollers are depressed against the cut sections of the
board 10 fed from the sawing unit. Designated by reference numerals
264 and 266 are stop members for the arms 256 and 258.
The vertical position of the entire roller arrangement making up
the board feeding and delivery mechanisms 22a and 22b can be varied
by a position adjusting mechanism which is designated generally by
reference numeral 268. The position adjusting mechanism 268
includes a stationary bracket 270 which supports a shaft 272
extending therethrough. The shaft 272, in turn, supports at one end
thereof a wheel 274 rotatable with the shaft and at the other end a
bevel gear 276. The gear 276 is in constant mesh with a bevel gear
278 on a lifting column 280 supported on the top wall of the casing
162. The lifting column 280 is screwed to a screw bearing 182
positioned within the casing 162. The casing 162 and all the parts
and elements supported thereon are thus moved upwardly or
downwardly through manipulation of the wheel 274.
Designated by reference numeral 283 in FIG. 6a is a
semi-cylindrical hood for the sawing unit. The hood 283 is provided
with a saw-dust discharge duct 285 which extends outwardly of the
casing 162 through, for example, the top wall of the casing 162 as
illustrated.
FIGS. 7a and 7b illustrate a preferred construction of the
saw-blade position indicating arrangement which is designated
generally by the reference numeral 24 in FIG. 1 and part of which
is seen in FIG. 4. Referring thus to FIGS. 4, 7a and 7b, the
blade-position indicating arrangement includes four flexible lines
284 which are connected each at one end to the upper extensions 140
of the shifters 128 (FIG. 4). The flexible lines 284 may be
actually ropes, wires, cables or chains. The flexible lines 284 are
first passed in a direction parallel to the rotary shaft 92 of the
saw blades 108 and are then turned laterally over respective guide
rollers 286. The lines are next turned at right angles toward the
supply side of the sawing unit over respective guide rollers 288
and are further turned back through respective guide rollers 290.
The guide rollers 286, 288 and 290 are carried on a suitable
stationary structure. These guide rollers 286 should be replaced
with sprocket wheels where it is desired that the chains are used
as the flexible lines. The flexible lines 284 are connected to
spring retainers 292 movable within a frame structure 294 in a
direction parallel to the rotary shaft 92 of the sawing unit.
Springs 296 are connected each at one end to these spring retainers
292 respectively and at the other to the side wall of the frame
structure 294, thereby urging the flexible lines 284 in the
directions of arrows in FIG. 7b. The spring retainers 292 are
integral with or connected to guide pins 298 which are slidable in
spaced elongated slots 300 formed in a front wall of the frame
structure 294 as seen in FIG. 7b. Movable with these guide pins 298
are indicator rods 302 which extend in front of the supply side of
the sawing unit. The indicator rods 302 support at their leading
ends indicator elements 304 which are located and movable
respectively in correspondence with the associated saw blades
108.
The operation of the saw apparatus which is constructed in a manner
thus far described will now be explained with concurrent reference
to FIGS. 1 to 7b.
When the board 10 having markings m identifying the knots or flaws
k to be removed is brought into abutting engagement with the stop
member or rail 28, then the limit switch 30 is actuated so as to
stop the preliminary conveyor 26 and cause the plunger 32a of the
pneumatic or hydraulic cylinder 32 to project forwardly. The marked
board 10 is accordingly moved by the plunger 32a to the roller
conveyor 36 under the carrier 46 of the light-sensitive scanning
arrangement. The advancement of the board 10 on the roller conveyor
36 is blocked by the gate members 42 and 42' which are in the
raised condition. When the board 10 strikes against the gate
members 42 and 42', it presses the limit switch 70 which causes the
plunger 32a of the cylinder 32 to withdraw to its retracted
position and the piston of the cylinder 52 to project. The carrier
46 supporting the lights 46a and photo-electric elements 46b is
accordingly moved from its rest position, thereby scanning the
marked face of the board 10 resting on the roller conveyor 36. The
rack 54 is moved as the carrier 46 is thus moved away from the
guide rail 38 so that the pinions 60 meshing with the rack 54 are
rotated with the associated potentiometers 62 through the shafts 64
and clutches 66. When the photo-electric elements 46b on the
carrier 46 thus moved transversely over the marked board 10 sense
the first marking on the board, then the first clutch 66 is
uncoupled and the brake thereof is actuated to stop the associated
potentiometer 62, which thus memorizes the location of the first
marking on the board in the form of a voltage. As the second and
third markings on the board are sensed by the photo-electric
elements 46b on the carrier 46, the second and third potentiometers
62 are stopped in succession to memorize the locations of the
markings. If three or fewer markings are present on the board 10,
then one or more of the potentiometers 62 will remain connected to
the associated pinions 60 until the carrier 46 and accordingly the
rack bar 54 are moved throughout their full strokes. When, however,
the carrier 46 reaches a position remotest from its rest position,
he limit switch 70 is actuated so as to uncouple the clutches 66
associated with the potentiometers 64 which were kept connected to
the pinions 60. The limit switch 70 also causes the piston rod of
the cylinder 52 to withdraw for moving the carrier 46 to its rest
position and the gate members 42 and 42' to be lowered below the
level of the roller conveyor 36. The carrier 46 depresses the limit
switch 72 when it reaches the rest position and is thereby held
stationary cycle of operation. Simultaneously, the plunger 32a of
the cylinder 32 is withdrawn to the retracted position so as to be
ready for moving a subsequent board to the scanning station.
The signal voltages produced by the potentiometers 62 of the signal
generator unit 56 are fed to the comparators 160 (FIG. 2) for
comparison with the signal voltages supplied from the
potentiometers 158. Control signals are fed from the comparators
160 to the solenoid operated control valves 146 associated
respectively with the saw blades 108 of the sawing unit. The
control valves 146 then operate to move the piston rods 142 of the
hydraulic cylinders 144 in a manner to equalize the voltages of the
signals from the potentiometers 62 and 158, as will be described in
more detail.
The shifters 128 are thus driven to slide on the respective guide
shafts 130, thereby moving the associated sleeves 120 axially on
the rotary shaft 92. This causes the collars 106a to 106d of the
sawing unit to axially slide on the rotary shaft 92. The saw blades
108a, 108b, 108c and 108d or some of them are consequently moved
over distances which are in agreement with the differences between
the voltages supplied from the potentiometers 62 and 158. The
movement of each saw blade is fed back to the associated
potentiometer 158 through a mechanical linkage including the
collar, guide rod 114, sleeve 120, ring 124, shifter 128, rack 150
and pinion 152 and thus varies the signal voltage from the
potentiometer 158. The saw blades are consequently brought to a
standstill when the differences between the signal voltages from
the potentiometers 62 and 158 are eliminated. The saw blades are
shifted while the shaft 92 is being rotated. The saw blades are in
this manner shifted to positions which are aligned with the
markings m on the board 10 leaving the light-sensitive scanning
arrangement.
The sensors 88, 88', 90 and 90' located adjacent the sawing unit
detect the presence or absence of a board on the sawing unit. In
the absence of a board on the sawing unit, the sensors issue
signals to allow the passage of the board 10 from the roller
conveyor 36 to the conveyor 82 through the intermediate transfer
mechanism 16 along the guide rail 38. The board 10 to be cut thus
flaps the return-preventive member 164 upwardly and enters the
board feeding mechanism 22a. While being conveyed on the conveyor
82 toward the sawing unit, the board 10 is held between the
conveyor 82 and the pressing rollers 182 and 184 by the compression
springs 186 and 196, irrespective of the variation in thickness or
of the irregular thickness of the board 10. The board 10 then turns
the second return-preventive member 228 and is fed to the saw
blades 108 by the auxiliary pressing roller 214. The board 10 is
thus cut into sections along the markings m on the board by the saw
blades 108 which are shifted to the selected positions previously
mentioned. The cut sections of the board, as designated by
reference numerals 10a, 10b and 10c in FIG. 1, are passed away from
the sawing unit while being pressed upon by the split pressing
rollers 238 and 240 and further by the main pressing rollers 260
and 262 of the delivery mechanism 22b.
The solenoid operated clutches 62 of the signal generator unit 56
are again engaged upon completion of the shifting operation by the
blade shifting mechanism and, as a consequence, the potentiometers
62 are rotated together with the associated pinions 60 in reverse
directions as the carrier 46 is returned to the rest position
whereby the potentiometers 62 are restored to the zero
positions.
As the shifters 128 are moved during the saw-blade shifting
operation as above described, the flexible lines 284 connected
respectively thereto are moved in the direction of arrows in FIG.
7a by the actions of the tension springs 296, and the guide pins
298 are moved through the elongated slots 300 in the frame
structure 294. The indicator elements 304 positioned at the rear of
the sawing unit are, therefore, moved in synchronism with the saw
blades 108 being shifted, thereby premitting visual inspection of
the movements of the saw blades by the operator.
Although it has been described that the board 10 to be cut is
brought to a standstill on the roller conveyor 36 when it is to be
scanned by the photo-electric elements 46b on the carrier 46, the
board 10 may be scanned while it is advancing toward the subsequent
station where desired. The number, locations and timings of
actuation of the switch elements and sensors in the saw apparatus
above described may be selected depending upon operation
requirements. Likewise, the numbers of the saw blades and
potentiometers, and the parts and elements associated therewith,
may be varied as desired. The potentiometers may be replaced by
suitable computing means which are capable of providing information
indicative of the number and locations of the markings on the board
to be cut. The signal generator unit of the light-sensitive
scanning and signal generating arrangement 14 may be modified in
numerous manners where desired. FIG. 8 illustrates an example of
such modifications of the scanning and signal generating
arrangement. The signal generator unit above described must be kept
inoperative for memorizing the locations of the markings of
subsequent board until the saw-blade shifting operation is
completed. This will apparently result in considerable loss in the
performance efficiency of the sawing operation.
To eliminate this inconvenience, the signal generator unit shown in
FIG. 8 uses two sets of potentiometers which are alternately put
into operation. In FIG. 8, the parts and elements which correspond
to those previously mentioned and illustrated are designated by
like reference numerals and no detailed description thereof will be
given.
Referring to FIG. 8, the modified signal generating unit includes a
suitable number of pinions 60 which are in constant mesh with a
rack 54 movable with the carrier 46 carrying the lights 46a and
photo-electric elements 46b. Each pinion 60 is connected with two
potentiometers 62 and 62' through solenoid operated clutches 66 and
66', respectively, having brakes adapted to positively stop the
associated potentiometers when disengaged. Couplings 306 and 306'
connect the clutches 66 and 66' with the associated potentiometers
62 and 62', respectively, and couplings 308 and 308' connect the
clutches 66 and 66', respectively, with the associated pinions 60
through torque limiters 68.
When, in operation, the board 10 strikes the limit switch 44 and is
brought to a full stop, then the carrier 46 starts to travel from
its rest position for scanning the marked face of the board. In
this instance, either of the two sets of potentiometers 62 and 62'
is connected to the pinions 60 on the rack 54 so that, as the
carrier 46 moves over the board 10, the rotation of the pinions 60
is imparted to, for example, the potentiometers 62 with the other
set of potentiometers 62' kept disconnected from the pinions 60.
The potentiometers 62 accordingly produce signal voltages which are
proportional to the angles of rotation of the associated pinions
60. The solenoid operated clutches 66 are disengaged as the
photo-electric elements 46b on the carrier detect the markings on
the board 10 for disconnecting the associated potentiometers 62
from the pinions 60. The potentiometers 62 are thus brought to a
standstill by the action of the brakes attached to the clutches 66
and memorize the locations of the markings detected. The clutches
66 remaining in the engaged condition until the carrier 46 has
moved through its full stroke are disengaged when the carrier
strikes the limit switch 70. The carrier 46 then returns to its
rest position and concurrently the board 10 on the conveyor 36
advances to the subsequent cutting station. While the board 10 is
thus being transferred to the sawing unit, the saw blades of the
sawing unit are shifted one by one in accordance with the signal
voltages from the potentiometers 62 and the succeeding board is
simultaneously conveyed on the conveyor 36 and reaches the position
to be scanned. The carrier 46 travels again to scan the marked face
of the board while the potentiometers 62' are operative to memorize
the locations of the markings detected by the photo-electric
elements 46b on the carrier 46. Upon completion of the cutting
operation on the preceding board, the saw blades of the sawing unit
are shifted to positions selected in accordance with the signal
voltages from the potentiometers 62'. The two sets of
potentiometers 62 and 62' are in this manner alternately put into
operation so that the loss in the performance efficiency otherwise
resulting from the downtime period of the signal generating units
can be eliminated.
A preferred example of the electric circuits adapted to control the
saw blade shifting mechanism of the saw apparatus above described
is illustrated in FIGS. 9a and 9b. The control circuit herein shown
is specifically arranged for use with the signal generator unit
shown in FIG. 1 for simplicity of description. It is, however,
apparent that the principle of operation of the shown control
circuit is applicable to the signal generator unit of the
construction shown in FIG. 8 which minor modification.
Referring to FIG. 9a, the signal generator unit 56 has four (or a
suitable number of) potentiometers 62a to 62d which are connected
in parallel to a source of power. The potentiometers 62a and 62d
are connected to a clutch control circuit 312 through respective
clutches 66. The clutch control circuit 312 comprises flip-flop
circuits 314a to 314d connected to the clutches for the associated
potentiometers 62a to 62d through drivers 316a to 316d,
respectively. The flip-flop circuits 314a to 314d have set
terminals connected to a suitable logical circuit such as an
AND-gate circuit 310. This AND-gate circuit 310 has one input
terminal connected to the limit switch 44 (FIG. 1), and the other
input terminal is energized when the saw-blade shifting operation
is complete. The reset terminals of the flip-flop circuits 314a to
314d are connected to output terminals of a shift register 318
having an input terminal connected to a suitable logical circuit
such as an AND-gate circuit 320. The AND-gate circuit 320 has one
input terminal connected to the photo-electric elements 46b on the
carrier 46 (FIG. 1) through an amplifier 322, and the other input
terminal is energized when the carrier 46 is being moved forward.
Turning to FIG. 9b, the potentiometer 62 which may be any one of
those designated by reference numerals 62a to 62d has a wiper arm
324. This mark-position indicating potentiometer 62 is connected in
parallel with the associated blade-position indicating
potentiometer 158 having a wiper arm 326 to the comparator 160
which was also previously mentioned. THe comparator 160 is
connected to a switch control unit 328 through lines 330 and 330'.
The solenoid operated valve 146 (see FIG. 1) has solenoid coils
146a and 146b for actuating the valve member. The solenoid coil
146a is connected to a power source 332 through a line 334 and a
relay switch 336 which is controlled from the switch control unit
328 through a line 338. The solenoid coil 146b, on the other hand,
is connected to a power source 340 through a line 342 and a relay
switch 344 which is controlled from the switch control unit 328
through a line 346. The switch control unit 328 is responsive to
the limit switch 70 which, in turn, is responsive to the movement
of the carrier 46 (FIG. 1) over its full stroke. This switch
control unit 328 may be connected to the AND-gate circuit 310 for
supplying thereto a signal indicative of the completion of the
blade shifting operation. The solenoid operated valve 146
communicates with the hydraulic cylinder 144 for moving the shifter
128 (FIG. 2) through fluid lines 348 and 350. The piston rod 142 of
the hydraulic cylinder 144 is connected to the shaft 154 of the
potentiometer 158 (see FIG. 2).
The wiper arm 324 of the mark-position indicating potentiometer 62
is normally set to a zero-position which is indicated at 63 in FIG.
9b. When the limit switch 44 (FIG. 1) is closed upon engagement
with the board and if the saw blades are all at rest, the set
signals are fed to the flip-flop circuits 314a to 314d through the
AND-gate circuit 316 whereupon the solenoid operated clutches 66 of
the mark-position indicating potentiometers 62a to 62d are coupled
by the driver circuits 316a to 316d, respectively. The wiper arms
of the potentiometers 62a to 62d are thus turned through angles
which are proportional to the distances traveled by the carrier 46
(FIG. 1). As the carrier advances, the photoelectric elements 46b
carried thereon detect the markings on the board so that the
AND-gate circuit 320 issues reset signals for the flip-flop
circuits 314a to 314d in a sequential fashion which is regulated by
the shift register 318. As the flip-flop circuits 314a to 314d are
thus cut off successively, the solenoid operated clutches 66 are
disengaged one by one. The wiper arms of the mark-position
disengaged potentiometers 62a to 62d are consequently brought to a
stop as the associated clutches 66 are disengaged. Upon completion
of the scanning operation, the limit switch 70 becomes operative to
actuate the switch control unit 328 subsequent to the comparator
160. This comparator 160 receives signal voltages from the
mark-position and blade-position indicating potentiometers 62 and
158 and compares the voltages with each other to produce a control
signal determined by the difference between the voltages. If the
signal voltage from the potentiometer 62 is lower than the voltage
from the potentiometer 158, then the comparator 160 supplies a
control signal to the switch control unit 328 through the line 330
to energize the relay switch 336 through the line 338. The relay
switch 336 is therefore closed so that the solenoid operated valve
146 causes the piston rod 142 to move outward of the cylinder 144
until the signal voltage from the potentiometer 158 equals the
voltage from the potentiometer 62. The saw blade associated with
the potentiometer 158 is accordingly shifted to a position dictated
by the signal voltage from potentiometer 62. When, conversely, the
signal voltage from the potentiometer 62 is higher than the voltage
from the potentiometer 158, then a control signal is transmitted
from the comparator through the line 330' to the switch control
unit 328 to close the relay switch 344 through the line 346 for
causing the valve 146 to withdraw the piston rod 142 until the
wiper arm 326 of the potentiometer 158 is synchronized with the
wiper arm 324 of the potentiometer 62. In the absence of a
difference between the voltages from the potentiometers 62 and 158,
the switch control unit 328 is operative to keep the relay switches
336 and 344 open so that the piston rod 142 and the associated saw
blade are held stationary. Upon completion of the saw blade
shifting operation, the difference between the input voltages to
the comparator 160 becomes zero so that the switch control unit 328
transmits a signal to the AND-gate circuit 310 which in turn
supplies the set signal to the flip-flop circuits 314a to 314d for
the subsequent cycle of scanning and blade shifting operations.
The above described circuit arrangement is merely illustrative, and
it is apparent that the signal controlling the saw-blade shifting
operation may be obtained in any other desired manner in accordance
with the markings on the board to be cut is.
* * * * *