U.S. patent number 3,664,395 [Application Number 05/025,388] was granted by the patent office on 1972-05-23 for log pre-centering apparatus for veneer lathes.
This patent grant is currently assigned to Salem Equipment, Inc.. Invention is credited to Gaylard O. Reed.
United States Patent |
3,664,395 |
Reed |
May 23, 1972 |
LOG PRE-CENTERING APPARATUS FOR VENEER LATHES
Abstract
Each of a pair of independently, vertically movable
log-supporting bases mounts a pair of opposed knees for confining a
log between them. The knees are movable horizontally inward in
direct proportion to the vertical movement of the associated base,
so that when the confronting faces of the knees are brought into
abutment with a log supported on the bases the axial centerline of
the log is aligned with the axial center of log transfer mechanism
which, in turn, is aligned with the rotational axis of veneer lathe
chucks in the log transferring position of said mechanism.
Inventors: |
Reed; Gaylard O. (Portland,
OR) |
Assignee: |
Salem Equipment, Inc. (Salem,
OR)
|
Family
ID: |
21825747 |
Appl.
No.: |
05/025,388 |
Filed: |
April 3, 1970 |
Current U.S.
Class: |
144/215.2;
82/170 |
Current CPC
Class: |
B27L
5/022 (20130101); Y10T 82/27 (20150115) |
Current International
Class: |
B27L
5/02 (20060101); B27L 5/00 (20060101); B27l
005/02 () |
Field of
Search: |
;144/29A,209 ;82/45 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schran; Donald R.
Claims
Having now described my invention and the manner in which it may be
used, I claim:
1. Log pre-centering apparatus for veneer lathes, comprising
a. a frame,
b. elevator means supported by the frame for vertical reciprocation
and adapted to support a log thereon,
c. a pair of spaced log-engaging knees supported by the elevator
means for movement vertically therewith and toward and away from
each other, and
d. connector means interengaging the knees and elevator means for
moving the knees toward and away from each other by vertical
reciprocation of the elevator means,
e. the connector means being arranged to move each knee a distance
equal to the distance of vertical movement of the elevator means
between a predetermined log-supporting position of the elevator
means and a predetermined log-centering axis.
2. The apparatus of claim 1 including drive means engaging the
elevator means for reciprocating the latter.
3. The apparatus of claim 1 including log support means adjacent
the elevator means for supporting a log initially in position for
engaging support by the elevator means.
4. The apparatus of claim 1 wherein the elevator means comprises a
pair of spaced elevators supported for independent vertical
reciprocation and each supporting a pair of knees.
5. The apparatus of claim 4 wherein the connector means comprises
flexible line means connected at one end to each knee and engaging
the frame at its opposite end, and guide means on the associated
elevator means engaging the line means intermediate its ends.
6. The apparatus of claim 4 wherein the connector means comprises
parallelogram link means pivotally interengaging each knee and
associated elevator means, and connecting means interengaging the
link means and frame.
7. The apparatus of claim 6 wherein each parallelogram link means
includes an extension of one of the links having a point thereon
arranged on a line extending perpendicular to a line through the
pivots of said link and spaced the same distance from the pivot
common to both lines as the distance between said pivots, the
connecting means interengaging said extension and frame.
8. The apparatus of claim 1 including abutment means on the frame
and connector means arranged for mutual engagement at a
predetermined elevation of the elevator means, whereby to prevent
movement of the knees toward each other until the elevator means
reaches said predetermined elevation.
9. The apparatus of claim 1 wherein the connector means comprises
flexible line means connected at one end to each knee and engaging
the frame at its opposite end, and guide means on the supporting
elevator means engaging the line means intermediate its ends.
10. The apparatus of claim 1 wherein the connector means comprises
parallelogram link means pivotally interengaging each knee and
supporting elevator means, and connecting means interengaging the
link means and frame.
11. The apparatus of claim 3 including abutment means on the frame
and connector means arranged for mutual engagement at a
predetermined elevation of the elevator means above the log support
means, whereby to prevent movement of the knees toward each other
until the elevator means reaches said predetermined elevation.
12. The apparatus of claim 3 wherein the elevator means comprises a
pair of spaced elevators supported for independent vertical
reciprocation and each supporting a pair of knees, and wherein the
apparatus includes abutment means on the frame and each connector
means arranged for mutual engagement at a predetermined elevation
of the elevators above the log support means, whereby to prevent
movement of the knees toward each other until the elevators reach
said predetermined elevation.
13. Log precentering apparatus for veneer lathes, comprising
a. a frame,
b. a pair of spaced elevators supported by the frame for
independent vertical reciprocation and adapted to support a log
thereon,
c. a pair of spaced log-engaging knees supported by each elevator
for movement toward and away from each other, and
d. connector means interengaging the knees and associated elevator
for moving the knees toward and away from each other by vertical
reciprocation of the elevator, the connector means comprising
parallelogram link means pivotally interengaging each knee and
associated elevator, and connecting means interengaging the link
means and frame,
e. the connector means being arranged to move each knee a distance
equal to the distance of vertical movement of the associated
elevator between a predetermined log-supporting position of the
elevator and a predetermined log-centering axis.
14. The apparatus of claim 13 wherein each parallelogram link means
includes an extension of one of the links having a point thereon
arranged on a line extending perpendicular to a link through the
pivots of said link and spaced the same distance from the pivot
common to both lines as the distance between said pivots, the
connecting means interengaging said extension and frame.
Description
BACKGROUND OF THE INVENTION
This invention relates to veneer lathes and more particularly to
novel means for pre-establishing the axial centerline of a log
prior to transfer to veneer lathe chucks.
Log pre-centering apparatus provided heretofore generally are
characterized by structures in which opposed log-centering members
are movable vertically above and below the log to be centered. Such
structures not only utilizes excessive headroom, but also require
complex and costly transfer apparatus capable of circumventing the
centering components above the log. Such apparatus also are slow in
operation and therefore restrictive of production, and inaccurate
to a degree which results in significant waste of peeler log
material.
SUMMARY OF THE INVENTION
In its basic concept the log pre-centering apparatus of this
invention utilizes the coordinated vertical movement of a pair of
log-supporting bases and the horizontal movement of a pair of
opposed log-confining knees on each base to establish the axial
centerline of a log for transfer to the rotational axis of veneer
lathe chucks.
It is by virtue of the foregoing basic concept that the principal
objective of this invention is achieved; namely, to overcome the
above enumerated disadvantages of prior apparatus.
The foregoing and other objects and advantages of this invention
will appear from the following detailed description, taken in
connection with the accompanying drawings of the preferred
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary view in side elevation of log pre-centering
apparatus embodying the features of this invention.
FIG. 2 is a fragmentary view in end elevation as viewed from the
right in FIG. 1.
FIG. 3 is a foreshortened, fragmentary view in side elevation of a
modified form of log pre-centering apparatus embodying the features
of this invention.
FIG. 4 is a fragmentary plan view as viewed from the top in FIG.
3.
FIG. 5 is a fragmentary side elevational view, similar to FIG. 3,
illustrating by solid and broken lines the operation of the log
precentering apparatus.
FIG. 6 is a foreshortened fragmentary view in longitudinal section
taken on the line 6--6 in FIG. 7 of log transfer apparatus for
association with the log pre-centering apparatus of this
invention.
FIG. 7 is a foreshortened plan view of the log transfer apparatus
of FIG. 6.
FIG. 8 is a transverse sectional view taken on the line 8--8 in
FIG. 6.
FIG. 9 is a transverse sectional view taken on the line 9--9 in
FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
For purposes of explanation, reference first is made to FIGS. 6-9
of the drawings which illustrate apparatus by which a log is
transferred from pre-centering apparatus to a veneer lathe. The
transfer apparatus illustrated incorporates two types of transfer
mechanism, one preferably for the transfer of relative large
diameter peeler logs and identified generally by numeral 10 and the
other preferably for the transfer of relatively small diameter
peeler logs and identified generally by the numeral 12.
Conveniently, both mechanisms may be mounted upon a common
framework for selective use, although it will be understood that
either one of them may be omitted, if desired.
The framework includes a pair of laterally spaced longitudinal
I-beams 14 secured together at their opposite ends by transverse
channel beams 16 and supported by vertical posts 18 at a desired
elevation.
The transfer mechanism 10 normally employed for the transfer of
relatively large diameter peeler logs includes a transverse
carriage frame 20 supported between the longitudinal beams 14 for
reciprocation relative thereto by rollers 22 which track on the
lower inner flanges of the I-beams 14. Motive power for the
carriage is provided by a pair of laterally spaced chains 24 which
are secured at their opposite ends to the longitudinal ends of the
framework. Intermediate their ends the chains are trained over
longitudinally spaced idler guide sprockets 26 and looped about
drive sprockets 28 secured to a common drive shaft 30. The drive
shaft extends transversely of the carriage and is coupled through a
drive chain 32 and appropriate sprockets and gear reduction
mechanism to an electric drive motor 34 mounted on the
carriage.
A pair of laterally spaced log clamping members 36 are supported by
the carriage and mounted for lateral adjustment toward and away
from each other. Thus, a pair of transversely elongated support
units are spaced apart longitudinally on the carriage. One of the
clamping members is secured to the outer sleeve member 38 of each
unit and the other clamping member is secured to the inner rod
member 40 of each unit. Each rod member is mounted for longitudinal
movement relative to the carriage frame, and each sleeve member is
mounted for longitudinal movement relative to its associated rod
member. A hydraulic piston-cylinder unit 42 mounted on the carriage
engages each clamping member for moving the latter.
Accordingly, by appropriate application of fluid pressure to the
drive units 42 the pair of clamping members may be moved toward
each other to engage the opposite ends of a peeler log for transfer
from log pre-centering apparatus to a veneer lathe, or may be moved
away from each other to release the log after it has been secured
between the rotary chucks of a veneer lathe.
The carriage 20 functions to reciprocate the clamping members 36
between a log pick-up position at log precentering apparatus and a
log transfer position at a veneer lathe. Referring to FIG. 6 of the
drawings, let it be assumed that the point X represents the axial
centerline of a pre-centered log at pre-centering apparatus
described hereinafter and that the point Y represents the
rotational axis of laterally spaced chucks of a veneer lathe. It
will be understood that limit switches or other conventional
control mechanism are provided for stopping the carriage at these
positions.
The lower log-engaging portion of each clamping member is provided
with log-engaging spikes 44 surrounding an opening 46 in the side
facing the direction of movement toward the veneer lathe, the
opening being of sufficient size to receive the veneer lathe chuck
therein. Thus, when the log has been secured between the lathe
chucks, the clamping members may be retracted and returned to the
log precentering apparatus, as will be understood.
The transfer mechanism 12, normally used with relatively small
diameter peeler logs, includes a rock shaft 50 which extends
transversely of the framework and is journaled in bearings mounted
on the framework. The rock shaft supports a pair of laterally
spaced log clamping arms 52 which, like the clamping members
previously described, function to releasably engage the opposite
ends of a peeler log. Thus, the arms are mounted pivotally on
brackets 54 projecting from the rock shaft and are interconnected
intermediate their ends by the transversely extensible fluid
pressure piston-cylinder unit 56.
The rock shaft is connected through a gear reduction unit 58 to an
electric drive motor 60 mounted on the framework. The electric
motor functions to move the clamping arms arcuately between a log
pickup position at log pre-centering apparatus and a log transfer
position at a veneer lathe.
The lower ends of the clamping arms are provided with spikes 44 and
openings 46 similar to and for the same purpose as the spikes and
openings previously described.
It will be understood that when the transfer mechanism first
described is to be used, the electric drive motor 60 is operated to
rotate the clamping arms 52 upwardly above the framework to permit
reciprocation of the carriage 20 between the log pick-up position
and log transfer position previously described.
Since the transfer mechanism 12 functions to transfer logs of
relatively small diameter, it is positioned closer to the veneer
lathe than the transfer mechanism first described. Accordingly, the
point Z represents the axial centerline of a precentered log at
pre-centering apparatus described hereinafter.
Referring now to FIGS. 1 and 2 of the drawings the log precentering
apparatus illustrated therein includes a framework of horizontal
beams 70 supported above a foundation base 72 by means of spaced
vertical beams 74 and hollow posts 76. Supported on the horizontal
beams of the framework is a box frame 78 which supports a pair of
laterally spaced, upwardly projecting log supports 80. The upper
portions of these log supports are interconnected for stability by
means of transverse braces 82. The upper surfaces of the supports
form shallow, aligned Vs for centering a log L across them as the
log is delivered thereto from an infeed conveyor illustrated by the
broken line 84.
Disposed laterally outward of each log support 80 is a
longitudinally elongated elevator base 86. Each base is supported
centrally on the upper end of a hollow post 88. The post preferably
is of square or other non-circular cross section and is guided for
vertical reciprocation within the correspondingly non-circular
hollow guide tube 90. The guide tube is secured to the box frame 78
and projects vertically upward and downward therefrom.
The lowermost position of each post 88, and hence each elevator
base 86, is defined by abutment of the under side of the base with
the upper end of the guide tube.
Vertical reciprocation of each post is provided by an elongated
hydraulic piston-cylinder unit. The elongated cylinder 92 is
supported at its lower end on a base plate 94 on the foundation 72
and extends vertically upward into the hollow post 88. The piston
rod 96 extending vertically upward from the cylinder is connected
at its upper end to the post by means of pivot shaft 98. Thus, each
elevator base 86 is movable independently of the other from the
lowered position illustrated in FIGS. 1 and 2 vertically upward by
application of hydraulic pressure to the bottom end of the
associated cylinder.
Mounted on each elevator base is a pair of log-abutting knees 100
and 102. Each knee includes a horizontal mounting member 104 and an
upstanding log-abutting member 106 secured thereto and reinforced
by the angular brace 108. Each mounting member is provided with a
rectangular opening 110 slidably receiving the elevator base 86. A
slot 112 in the bottom side of the mounting member receives the
downwardly extending flange 114 of the elevator base. The pair of
knees thus are movable on the elevator base toward and away from
each other.
Means is provided for moving the pair of knees associated with each
elevator base simultaneously toward each other in direct proportion
to the vertical upward movement of the elevator base. In the
embodiment illustrated in FIGS. 1 and 2 a pair of elongated chains
120 are connected at one end to laterally spaced lugs 122
projecting downward from the mounting member 104 of each knee. The
chains extend inward toward the longitudinal center of the elevator
base and are reeved over sprockets 124 mounted for rotation on a
shaft carried by the flange 114 of the elevator base. The lower end
of each chain is connected to an elongated rod 126 which extends
downward slidably through an opening in an abutment block 128
secured to the vertical beam 74 of the framework. The lower end of
each rod carries an enlarged head 130 arranged to engage the
associated abutment block at a predetermined elevation of the
elevator base 86, whereupon further upward movement of the latter
effects movement of the pair of knees toward each other, as
explained more fully hereinafter.
It will be apparent that the chains 120 may be replaced with cables
or other suitable forms of flexible lines, in which case the
sprockets 124 will be replaced with appropriate forms of
pulleys.
Means also is provided for retracting the pair of knees
simultaneously away from each other as the associated elevator base
is lowered toward the position illustrated. In the embodiment
illustrated such means is provided by a pair of cables 132
connected at their upper ends one to each of the mounting members
104 of the knees. Each cable is reeved about a pulley 134 mounted
on a longitudinal extension of a flange 114 of the elevator base,
thence about a pulley 136 mounted rotatably on a tab extending
downward from the flange and thence downward through the associated
hollow post 76 where it is connected at its lower end to a heavy
weight 138 confined freely in the post.
A central longitudinal slot 140 in each knee mounting member above
the rectangular opening receives the associated cable above the
elevator base during reciprocation of the knees, as will be
understood.
The operation of the log precentering apparatus illustrated in
FIGS. 1 and 2 is as follows: With both elevator bases 86 lowered to
the position illustrated, a log L is delivered by the infeed
conveyor 84 and deposited and centered on the spaced log supports
80. Hydraulic pressure then is applied to the bottom ends of the
cylinders 92, whereupon the pair of elevator bases are caused to
move upward into abutment with the bottom of the log at
longitudinally spaced points on the latter (FIG. 2) and to lift the
log therefrom.
It is to be noted, particularly from FIG. 1, that as the
log-abutting surface of each elevator base 86 moves upward through
the distance a, which is the same as the distance between the head
130 of each rod 126 and its associated abutment block 128, the
associated pairs of knees are not caused to move inward toward each
other. However, when the elevator bases reach the level 86', the
rod heads 130 also engage the abutment blocks 128. Thereupon,
further upward movement of the elevator bases and, of course, the
sprockets 124, causes the pairs of knees to move inward toward each
other. Each knee moves inward the same distance as its associated
elevator base moves upward, and therefore the point of intersection
of the knee and base traverses a line which is disposed at an angle
of 45.degree. with respect to vertical or horizontal.
Accordingly, it can be seen that if each elevator base moves upward
from its position 86' a distance equal to one-half the distance
between the associated knees at their illustrated positions of
extreme retraction, the log-abutting members 106 of the associated
pair of knees will have been brought into mutual abutment on the
plane of the vertical line 142 (FIG. 1). The point X of
intersection of this line with the horizontal line 144 representing
the log supporting surface of the associated elevator base defines
the axis on which the axial centerline of a log is to be
precentered.
In FIGS. 1 and 2 of the drawing a log L to be precentered is shown
in full lines with an exaggerated taper, merely to better
illustrate the relative differences of movement of each elevator
assembly to effect centering of a tapered log on its axial
centerline.
It will be apparent that the pair of knees 100, 102 adjacent the
smaller diameter end of the log must move closer together to engage
that end of the log than must the pair of knees 100, 102 associated
with the larger diameter end of the log. In order for the first
mentioned pair of knees to move closer together, the associated
elevator base 86 must also move upward a corresponding distance
higher than the elevator base 86 associated with the larger
diameter end of the log. Accordingly, when the pair of knees have
engaged the smaller diameter end of the log and the other pair of
knees have engaged the larger diameter end of the log the axial
centerline of the log is established precisely on the axis X in the
manner illustrated in broken lines.
Since the pairs of knees are in firm abutment with the log and
therefore cannot move farther inward toward each other, the
associated elevator bases are restrained against further upward
movement. The increased hydraulic pressure in the cylinders 92 thus
may be utilized, for example, through a pressure sensitive switch
(not shown), to actuate the log transfer apparatus to pick up the
precentered log and transfer it to the veneer lathe. In this
regard, it will be understood that the point X of intersection of
the lines 142 and 144 illustrated in FIG. 1 also corresponds to the
axis Y of rotation of the veneer lathe chucks (FIG. 6), as
previously explained.
It will be further understood that when the transfer mechanism has
engaged the opposite ends of the precentered log, manual or
automatic control mechanism (not shown) is operated to retract the
piston rod 96 of the cylinder 92 and thus lower the elevator bases
86. Lowering of these bases simultaneously effects retraction of
the knees 100, 102 to the position illustrated in FIGS. 1 and 2,
with the assistance of the weights 138.
Referring now to FIGS. 3-5 of the drawings, the log precentering
apparatus shown therein is employed primarily with logs of
relatively small diameter and thus is associated with the log
transfer mechanism 12 illustrated in FIG. 6. The apparatus includes
a pair of laterally spaced log supports 150 similar to the log
supports 80 previously described. Each of the log supports is
supported by a plurality of longitudinally spaced beams including
the pair of beams 152 illustrated.
Outward of each pair of beams is a longitudinally elongated
elevator base 154 in the form of a box frame. A T-shaped guide bar
156 secured to the inner side of each base 154 is slidably received
in a pair of longitudinally spaced, vertical guides 158 secured to
the beams. The guide bar and guides thus serve to guide the
elevator base for vertical reciprocation.
Each base is supported for vertical reciprocation by an elongated
hydraulic piston-cylinder unit. The elongated cylinder 160 is
supported at its lower end on a base plate 162 on the foundation 72
and extends vertically upward therefrom. A piston rod 164 extending
vertically upward from the cylinder is connected at its upper end
to the base by means of a pivot shaft 166. Accordingly, each
elevator base is movable independently of the other from the
lowered position illustrated in FIG. 3 vertically upward by
application of hydraulic pressure to the bottom end of the
associated cylinder.
Mounted on each elevator base is a pair of log-abutting knees 170
and 172. Each knee includes a pair of laterally spaced side plates
174 and an upstanding log-abutting member 176 secured thereto. The
lower ends of the log-abutting members extend downward into the
hollow box frame of the elevator base sufficiently to prevent
debris from lodging between the lower edges of the side plates 174
and the upper log-supporting surfaces of the elevator base.
Means is provided for moving the pair of knees associated with each
elevator base simultaneously toward and away from each other in
direct proportion to the vertical movement of the elevator. Thus,
each knee is connected to its associated elevator base by means of
a pair of links 178 and 180 (FIG. 5) which are confined within the
elevator box frame base and between the side plates 174 of the
knee. The upper ends of the links are connected to the knee by
means of the longitudinally spaced pivot shafts 182 and 184,
respectively, and the bottom end of the link 178 and an
intermediate point of the link 180 are connected to the elevator
box frame base by means of the longitudinally spaced pivot shafts
186 and 188, respectively. The pivot shafts are arranged to form a
parallelogram, whereby the vertical log-abutting member 176 of the
knee remains vertical throughout the range of movement of the knee
toward and away from its associated knee.
The link 180 is extended from the pivot shaft 188 arcuately inward
and upward and terminates in an arcuate end 190. This end is
located such that a line 192 extended from the axis of pivot shaft
188 perpendicular (angle b) to a line 194 extending between the
axes of pivot shafts 184 and 188 terminates at a point 196 on said
arcuate end which is the same distance from the axis of pivot shaft
188 as is the axis of pivot shaft 184.
One end of a chain 200 is wrapped about the arcuate end 190 of each
link 180 and is secured to the latter. The lower end of the chain
is connected to an elongated rod 202 which extends downward
slidably through an opening in an abutment block 204 secured to the
vertical beam 152. The lower end of the rod carries an enlarged
head 206 arranged to engage the abutment block at a predetermined
elevation of the elevator base, whereupon further upward movement
of the latter effects movement of the knee inward toward its
associated knee.
In similar manner, retraction of each knee is effected by lowering
the elevator base, whereupon the parallelogram linkage pivots
clockwise (FIG. 5) to return the knee to its fully retracted
position.
As in the embodiment first described, the knees of each pair
reciprocate toward and away from each other during vertical
movement of the associated elevator base in such manner that the
point of intersection of the vertical log-abutting member 176 and
the log supporting surface of the elevator base 154 moves along a
line which forms an angle c of 45.degree. with vertical or
horizontal. Accordingly, each knee moves horizontally through the
same distance that the elevator base moves vertically.
The operation of the log pre-centering apparatus illustrated in
FIGS. 3-5 is as follows: With both elevator bases lowered to the
position illustrated in FIG. 3, a log L is delivered, deposited and
centered on the spaced log supports 150. Hydraulic pressure then is
applied to the bottom end of the cylinders 160, whereupon the pair
of elevator bases are caused to move upward until they abut the
bottom of the log at longitudinally spaced points on the latter
(FIG. 4) and lift the log therefrom.
It is to be noted from FIG. 3 that as the log-abutting surface of
each elevator base moves upward through the distance a, which is
the same as the distance between the head 206 of each rod 202 and
its associated abutment block 204, the associated pairs of knees
are not caused to move inward toward each other. However, when the
elevator bases reach the level 154' the rod heads 206 also engage
the abutment blocks 204. Thereupon further upward movement of the
elevator bases causes the links to pivot clockwise and move the
pair of knees inward toward each other, each knee moving forward
the same distance as its associated elevator base moves upward.
Accordingly, as in the previous embodiment, it can be seen,
particularly from FIG. 5, that if each elevator base moves upward
from its position 154' a distance equal to one-half the distance
between the associated knees at their illustrated position of
extreme retraction, the log-abutting members 176 of the associated
pair of knees will have been brought into mutual abutment on the
plane of the vertical line 210. The point Z of intersection of this
line with the horizontal line 212, representing the log supporting
surface of the associated elevator base, defines the axis on which
the axial centerline of a log is to be precentered.
In FIG. 4 of the drawing, a log to be precentered is shown in
broken lines in an exaggerated taper, for the same purpose as
previously explained. It will be apparent that the pair of knees
adjacent the smaller diameter end of the log must move closer
together to engage that end of the log than must the pair of knees
associated with the larger diameter end of the log. In order for
the first mentioned pair of knees to move closer together the
associated elevator base must also move upward a corresponding
distance higher than the elevator base associated with the larger
diameter end of the log. Accordingly, when the pair of knees have
engaged the smaller diameter end of the log and the other pair of
knees have engaged the larger diameter end of the log, the axial
centerline of the log is established precisely on the axis Z in the
manner illustrated in broken lines in FIGS. 3 and 5.
Since the pairs of knees are in firm abutment with the log and
therefore cannot move farther inward toward each other, the
associated elevator bases are restrained against further upward
movement. As in the previous embodiment, the increased hydraulic
pressure in the cylinders 160 thus may be utilized to actuate the
log transfer mechanism 12 to pick up the precentered log and
transfer it to the veneer lathe. In this regard it will be
understood that the point Z of intersection of the lines
illustrated in FIGS. 3 and 5 also corresponds to the axis Y of
rotation of the veneer lathe chucks, as previously explained.
From the foregoing it will be apparent that the log precentering
apparatus of this invention provides no obstruction above the log.
This simplifies the construction and enhances the speed and mode of
operation of transfer apparatus and correspondingly increases
veneer production. The degree of precision of centering afforded by
the log precentering apparatus of this invention also minimizes
waste of peeler log material, thereby further decreasing the cost
of veneer production.
It will be apparent to those skilled in the art that various
changes may be made in the structural details described
hereinbefore. For example, if the peeler logs are untapered, a
single elevator, designed to support the log, may replace the pair
of independently movable elevators.
As another example, the fixed log supports 80 or 150 may be
omitted, the log to be centered being deposited directly upon the
elevator base 86 or 154. Use of the log supports is preferred,
however, particularly in an embodiment illustrated in FIGS. 1 and 2
in order to avoid jarring and other adverse effects on the elevator
assembly which might occur when large diameter logs are dropped
directly upon the elevator bases 86.
As a further example, the arrangement of chains 120 and headed rods
126 may be replaced by rack and pinion assemblies or other suitable
drive means interconnecting the elevator bases and knees and the
knee-retracting weights 138 may be replaced with springs, or other
suitable mechanism.
If it is desired to have each pair of knees move toward each other
as the associated elevator moves downward, rather than upward as
illustrated, the lower ends of the chains 120 may be connected to
the vertically movable post 88. Such an arrangement might be
useful, for example, under circumstances in which it is
inconvenient to provide a pit for the lower portion of the
apparatus.
The foregoing and various other changes in the size, shape, number
and arrangement of parts may be made without departing from the
spirit of this invention.
* * * * *