CA1109548A - Veneer lathe charging apparatus and method for determining log spin axis - Google Patents

Abstract

Abstract of the Disclosure A veneer lathe charging apparatus includes a break-beam scanning system and a computer for determining an optimal log spin axis. The charging apparatus further includes charger arms independently operable and adjustable to transfer a log from a scanning station to a veneer lathe so that a predetermined spin axis is precisely aligned an the chucks of a veneer lathe.
Additionally, there is provided an extendible-retractable spindle assembly operable for rotating a log during scanning.

Description

BACKGROUND AND SUMMAP~Z OF THE INVENTION
The pre~ent invention relates to so~called veneer lathe charging apparatus employed to load a log onto a veneer lathe for peeling. More particularly, the present invention pertains to a charging apparatus including an electro-optical scanning system coupled to a computer for determining an optimum spin axis.
Charger arms on the apparatus are selectively adjustable to trans~er the log so that its spin axis is aligned in the chucks of the lathe.
10Known veneer lathe charging apparatus typically take the form of an upright frame structure having spaced apart charger arms which are pivotally connected at the top of the structure. A log to be peeled is fed into the structure in a direc~ion with its longitudinal axis generally perpendicular to the direction of travel. The log is deposited on yokes or so- :
called V's. Disposed above the V's are inverted V's. Both sets of V's are interconnected by a mechanism which simultaneously displaces the V's toward each other at an equal rate. Thus, the log is moved to a position whereby an axis approximating its center is maintained between the V's. The V's will always contact the log equidistant from a predetermined axis) which axis becomes the spin axis.
At this point~ the charger arms are angularly displaced :-from a pre-spot position so that the log is gripped at its oppo-site ends. The V's are then simultaneously retracted, and the charger arms are pivoted toward the verleer lathe. The log is thereby transferred into the lathe in a position wherein the approximate log center or spin axis is aligned within the chucks on the veneer lathe. The chucks are then actuated to grip the log about the spin axis. The log is then rotated and veneer is peeled therefrom, There are several significant disadvantages with the 1. ~

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~a~ 548 above-described apparatus. First of all, it can be readily appreciated that because logs do not have a uniformly round profile, the V's simply cannot accurately determine the longi-tudinal axis or optimum spin axis of a log. Therefore, when the log is transferred to the veneer lathe, and the chucks are ex-tended to grip the log and rotate same, the log will not be rotated about its optimum spin axls. As a result, precession will occur during peeling of veneer, which decreases the usable amount of veneer peeled from the log.
Because o the nation7s dwindling timber resources, and because it is economically unfeasible ~o waste material during veneer peeling, there have been proposals directed to more accu- -rately determining the optimum spin axis of a log. Prior art proposals have defined the optimum spin axis as being the axis of the largest right cylinder found within the vol~me of a log. In order to accurately locate such a spin axis, it has been proposed to determine the surface configuration of a log prior to its peeling into veneer. Once the surface configuration has been determined, it is a simple matter to calculate the sought for right cylinder. Sys~ems have been proposed for determining the surface configuration using light radiation sources for trans-mitting light to the log's surface and measuring the time for the reflected light to return to a transceiver. The log is rotated and the measurements are taken for different angular displace-; ments through 360. The surface configuration of a log is there-by determined.
A problem present with the light radiating and reflec-tion system resides in the fact that a log will o~ten have con-cave surfaces. Thus, when light is directed toward the log it will travel to an innermost portion of a concave surface before it is reflected back to the transceiver. Consequently, if there are plural concave regions, the right cylinder computed will lie

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S~3 inwardly of such regions. l'hus, as the log is rotated about the computed spin axis in a veneer lathe (corresponding to the longi-tudinal axis of ~he right cylinder), small strips of veneer will he peeled from the log adjacen~ to the concave portions. Optimum veneer yield will not be obtained.
Additionally, once the optimum spin axis according to the above-described system has been de~ermined, it is also diffi-cult to accurately transfer the log from its scanning position so that the spin axis is accurately aligned with the chucks o~ a veneer lathe. The spin axis intersects the ends of the log at different points offset fro~ the axis used during scanning.
Accordingly, it is a general object of the present invention to provide a charging apparatus which will accurately determine an optimum spin axis no~ necessarily defined by the axis of the largest right cylinder included within the volume of a log. To provide such an apparatus, the present invention uses an electro-optical "break beam" scanning system in which the log is rotated through light beams bein~ emitted from sources to detectors. Such a system will not determine the surface configu-ration of a rotating log based upon interior regions of concaveportions of the log. A computer receives data transmitted from the sources and detec~ors and calculates the optimum log spin axis which may include~a cylinder lying partially outside the surface configuration or periphery of the log.
Another object of the present invention is to provide a charging apparatus in which each of the charger arms is operable independently rom one another and is adjustable for precisely positioning a predetermined log spin axis in alignment wîth the chucks o~ a veneer lathe. Each arm is provided with a log grip-ping means or shoe which can be seIectively extended or retractedto vary the leng~th of the arm from the arm's pivot axis to a point defined by the shoe. Additionally, each arm is pivotally moved by a fluid ac~uated cylinder, whîch cylinder is selectively shiftable along the horizontal.
Another object of the present invention is to provide a scanning system in which an extendible-retractable spindle grips and rotates the log during a scanning operation.
These and other objects and attendant advan~ages of the present invention will be more readily understood ~rom a consid-era~ion of the drawings and the detailed description which follow.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a front view of a charging apparatus ? broken along its width and modified according to the principles of the present invention;
Fig. 2 is a view taken along lines 2-2 of Fig. 1 and illustrates pivotal movemen~ of a charger arm;
Figs. 3, 3a and 3b are schematic views of a log rota-ting sequence according to the present invention in which peri-pheral points on ~he log's surface break a light beam beîng emitted from a source to a detector, only a single source and detector being illustrated; --Fig. 4 is an enlarged view, partially broken away, illustrating details of an extendible-contractable auxiliary spindle used to grip and rotate a log during a scanning operation;
Fig. S is a block diagram of the scanning system along with a charger arm adjusting system operable in conjunction with a computer according to the present invention;
Fig. 6 is a view of a so-called heart-shaped log and illustrates an optimum spin axis according to the present inven-tion in comparison wlth the optim~m spin axis as de~ined by the largest right cylinder includable in the volume of the log; and Fig. 7 is a schematic view of the steps required to selectively adjust the orientation of a charger arm in order to align a predetermined spin axis in the chucks of a veneer lathe.

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-- . - .: ,, : .: ' . , DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a veneer lathe charging apparatus which is operable to rotate a log through 360, and by using a break-beam scanning system and a computer, determine a log spin axis in which optimum veneer yield is ensured. The charging apparatus includes charger arms which are independently adjustable to grip a log and transfer i.t from a soanning station to a veneer lathe so that the spin axis is aligned in the chucks of the lathe. With this brief overview in mind, details of the construction and operation of the present invention will now be set forth.
Turning to Figs. 1 and 2 of the drawings, there is indicated generally at 10 a charging apparatus in accordance with the present invention. Apparatus 10 includes a supporting frame structure generally designated a~ 12~ Structure 1~ includes upright members 16, 18, 20 which are arranged at opposite ends of lower horizontal supporting members (not shown). I-beams 22 interconnect members 16, 18, 20. Mounted on kop o beams 22 are bearings 24 through which a shaft 26 is rotatably mounted. Shaft 26 includes an enIarged portion 28 extending between bearings 24.
Apparatus 10 is symmetrical about a center line 30 indicated in Fi8. 1. The right hand side of Fig. 1 has been partially broken away ~o con~erve space. Further, Fig. 1 does not include several elements shown in the le~t-hand side of the figure for purposes of illustrating structure which would nor-mally be hidden. Fig~ 2 is a view taken along lines 2-2 of Fig.
1 and illustrates essential features of the present inven-tion. A description of these features will be described with reference to the view shown in Fig. 2, but it must be remembered that the right hand side o~ apparatus 10, as viewed in Fig. 1 is ..

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substantially identical.
Opposed bearing halves 30, 32, are connected together around shaft 28. Connected to an underside of bearing 3~ is an elongate charger arm generally designated at 34. Arm 34 includes a plate rnember 36 connected to bearing half 32. Extending in-wardly from member 36 is a beam 38 connes:ted to member 36 and a support bracket 40.
Connected adjacent the bottom of plate 36 is a later-ally extending tube member 42. A supporting bracket 44 inter-10 connects beam 38 and tube 42 and depends from additional bearinghalves 31 and 33. A bottom portion of bracket 44 is connected to a mount 43. A slide mount 45 constructed of two halves, 45a and 45b, is slidably mounted on tube 42. A plate 46 is connected to mount 45 and supports a mounting plate 48. Mounted on top of plate 48 is an electric motor 50. A drive sha:Et 51 extends through an aperture in mounting plate 48 and is connected to a drive pulley 52. A shaft encoder 50a is provided for indicating the amount of rotation of shaft 51. Pulley 52 is operatively connected to another pulley 54 by means of a timing belt 56.
20 Pulley 56 is mounted on a tru~nion 58 which includes pin members 60 supported in an apertured bracket 62.
Rotatably mounted and supported within trunnion 58 and rigidly connected ~o pulley 54 is a nut (not shown) which, with a screw 64, forms a power transmission means of the so-called ball bearing screw type, generally indicated at 65. Screw 64 is formed with concave helical grooves. Cooperating helical grooves are provided in the nut and ball bearings are interposed the grooves. Thusl when pulley 54 is driven, screw 64 will rnove vertically upwardly or downwardly depending upon the direction of 30 rotation. Screw 64 is nonrotatable and is driven by the rotating nut which is connected to pulley 54.
A guide means or tube 66 extends from plate 46 and 6.

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slidably receives a rod 68. Connected to the bottom of rod 68 is a gripping means or shoe 70 formed with a semi-circular por~ion 71. Shoe 70 includes spikes or dogs 72 bolted thereto~ Con-nected to shoe 70 is a rod 74 which is slidably disposed within a bushing 76. Bushing 76 is mounted to tube 66 by means of a bracket 78. A connecting link 80 is connec~ed to a rod eye 82 at a pivot connection 84. Screw 64 has a lower end rigidly secured to rod eye 82.
As motor 50 is operated to drive pulleys 52, 54, it can be seen that screw 64 will move vertically upwardly or downwardly depending upon the direction of rotation. Accordingly, rod 74 will be moved to thereby slide rod 68 in guide means 66. As shown in Fig. 2, semi-circular portion 71 defines a center or reference point 70a which is located on a radial lîne extending from pivot axis 28a through charger arm 34. Thus, reference point 70a may be moved relative to arm 34 and pivot axis 28a by movement of rod 68.
Referring more particularly now to Fig. 2, it can be seen that arm 34 may be pivoted about shaft 28 and axis 28a by an actuating means or swing assembly generally designated at 86.
Actuating means 86 ineludes a ~luid actuated cylinder 88 having mounted therewithin an extendible retractable rod 90. Rod 90 is fixed at its extended end to plate 36 in convenient manner.
Cylinder 88 is mounted to frame structure 12 so that an end of the cylinder may be translated substantially horizontally along a slide mechanism generally designated at 92. Slide mechanism 92 is operated by a ball bearing screw 94 driven by A motor 96.
Motor 96 is pxovided with a shaft encoder 96a and is mounted on a plate 98 which plate is ln turn secured to beam 22. A power transmission meansj generally designated at 100 is mounted to beam 22 by means of ~upporting plates, 102 and 103.
Power transm;.ssion means 100 includes screw 94 which is ~r~

inserted through an aperture in plate 103 and further includes housing sections 104, and 105. Housing section 104 is rigidly connected to plate 103 and includes therewithin a rotatable nut (not shown). Pulley 106 is rigidly connected to the nut so that upon rotation of pulley 106, the nut will also rotate within housing 104 to drive screw 94. A belt 108 in~erconnects a pulley 97 of motor 96 with pulley 106. Slider mechanism 92 includes guides 92a, 92b connected to plate 102. A rod 110 is slidably disposed through guides 92a, 92b. More than one rod may be used 10 to facilitate movement and prevent binding. An end of cylinder -88 is pivotally connected at 114 to bracket 112. Bracket 112 is rigidly connected to rod,llO and screw 94 has an end rigidly connected to bracket 112. Thus, it can be appreciated that upon actuation of motor 96, screw 94 will be horizontally moved to the right or left as viewed in Fig. 2. Upon such movement, slide mechanism 92 will guide an end of cylinder 88 in a horizontal direction. This motion will be transferred to the end of rod 90.
Returning to Fig. 1, it can be seen that another fluid actuated cylinder, generally designated at 116, is mounted by means of a bracke~ 118 to mount 43 and tube 42. ~n extendible- ' retractable rod 120 is connected to a plate 122 which in turn is connected to arm 34. Thuss upon extension or retraction of rod 120, charger arm 34 will be shifted laterally along tube 42 to either the left or right as shown in Fig. 1. Such a movement is necessary in order to grip a log, as will be described later.
Bearing assemblies such as halves 3I, 33 and bracket 44 provide additional support for interconnecting beam 38 and tube 42. Thrust shoes are indicated at 128.
While a charger arm 34 and .m actuating means 86 have been described with reference to the left of Fig. 1, it must be appreciated that the same structure is provided on the right~hand side of apparatus 10. Because the components are substantially ' 8.

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identicalJ a repetitive discussion is deemed to be unnecessary.
Details of an assembly for rotating a log and scanning the log's surface configuration will now be described. With reference now directed to Fig. 4 as well as Figs. 1 and 2, it can be seen that an auxiliary spindle assembly, or rotator means, generally designated at 130, includes an elongate spindle 132 which is rotatably and slidably disposed within an elongate cylinder 134. Spindle 132 includes dogs 133 at an outward end.
Cylinder 134 extends through an apertured mounting plate 136.
Plate 136 is mounted to the upright ~rame members. A casing or drum 138, includes a sprocket wheel 140 rigidly connected thereto.
Casing 138 is rotatably mounted on cylinder 134 for rotation along a longitudînal axis concentric relative to the cylinder's longitudinal axis. Further details of spindle assembly 130 will be provided at a later point.
A mounting bracket 141 extends from a side of frame structure 12 and includes an upright motor mount 142. A motor, 144, is mounted on plate 142 so that a motor shaft extends through an aperture in the plate. A shaft encoder is shown at 144a. A
gear reducer 146 is operatively coupled to motor 144 by means of a coupling 148. An output sprocket wheel 150 is operatively connected to sprocket wheel 140 by means of a chain drive 152.
Thus, it can be appreciated that upon actuation of motor 144, sprocket wheel 14U is driven to rotate spindle 132. However, as previously mentioned, spindle 132 is also extendible and retract-able within cylinder 134.
With reference now directed to Fig. 4, further details of auxiliary spindle assembly 130 will be particularly described.
Cylinder 134 is rigidly connected to molmting plate 136 as described previously. Mounting plate 136 is connected to frame members ~uch as ~rame member 16 by appropriate securing bol~s, one of which is shown-at 137. A bracket 139 supports cylinder 134 and is connected to plate 136. Cylinder 134 extends through an aper~ure 136a in mounting plate 136. Casing 138 is cylin-drical in configuration and is connected to sprocket wheel 140 by circumferentially disposed bolts 154. An outer, stationary rim or hub 156 extends from cylinder 134 and includes a bearing 158 for permitting cylinder 138 to rotate about rim 156. Another hub-bearing assembly is indicated at 157, 159. Spindle 132 is provided with an elongate bore 132a eætending from the right-hand end of spindle 132 to an intexmediate point. E~tending through bore 132 is a splined shaft 160 which is rigidly secured to an end 138a of casing 138. Multiple keys 162 rigidly connected to spindle 132 slidably fit in splines in shaft 160 and permit spindle 132 to move in a direction along the longitudinal axis of shaft 160 but prevent relative rotation therebetween.
Spindle 132 also includes opposed piston surfaces 164, 164a, 166, 166a. ~ppropriate 0 ring seals 168 are interposed between the piston surfaces. ~ fluid conducting inlet port 170 communicates with a conduit 172 and permits fluid to be intro-duced into a chamber 132b between the outer diameter of spindle 132 and the inner diameter of cylinder 134. ~nother inlet port 171 permits fluid to be introduced into chamber 132c ~rom conduit 173. Guides 174, 176 are provided for mounting spindle 132 in cylinder 134. Appropriate threaded connectors such as spanner screws 175, 177, maintain the guides in appropriate position.
Briefly, the extendible-retractable and rotatable spindle i5 operable as follows. A suitable flu-Ld valving arrange-ment (not shown) permits actuating fluid to be selectively intro-duced and discharged through conduits 172, 173. With spi.ndle 132 primarily retracted, as shown in Fig. 4, an introduction of fluid in conduit 172 and port 170 into chamber 132b will result in fluid pressure acting against piston surfaces 166, 166a. Spindl~
132 will be ex~ended to the left. Similarly, actuating fluid 10 .

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~ 3 introduced through conduit 173 and port 171 will enter chamber 132c and act against piston surfaces 164, 164a to retrac~ spindle 132 within cylinder 134 or to the right as shown in Fig. 4.
During such retraction, fluid pre~iously in chamber 132b is exhausted through port 170 and through conduit 172.
It is to be noted that spindle 132 is also rotatable about its longitudinal axis. Rotation is effectuated by casing 138 which is rigidly connected to sprocke~ wheel 140. Upon sprocket wheel 140 being ro~atably driven, shaft 160, connected to spindle 132, also rotates thereby rotating spindle 132.
~ ith reference now redirected to Figs. 1 and 2, addi-tional structural features will be described. Lower yokes or V
members 178 are vertically opposed from upper Y members 180.
Such V members are known in charging apparatus, and are only sche-matically illustrated. Bottom V members 178 are arranged to re-ceive a log from an infeed system, (not shown) to the left of Fig. Z. V members 178, 180 are interconnected by an elevator sys-tem (a portion shown at 14) which is operable for displacing the V members at equal rates toward each other. Thus, it can be seen that when a log is loaded on V members 178 and the V members are vertically displaced toward each other, the log will be elevated to an eventual position in ~hich an approximate longitudinal cen-ter is reached. This center will never vary and is independent of log diameter. By design, this center will coincide with the longitudinal axis o~ the spindles. As shown in Fig. 2, the longi-tudinal axis of spindle 132, ~hich corresponds to the longitudin-al axis or center provided by the VIS7 iS indicated at 135.
An electro-optical scanning system is provided for ~ -determining the surface configuration of a log. The scanning system is operable a~ter a log has been located in V members 178, 180 snd is moved to a position w~ereby the spindles are extended inwardly to grip the log as shown in Fig. 1. As shown ,.. . ~

diagr~natically in Figs. 3, 3a and 3b, and schematically in Figs.
1 and 2, the scanning system includes plural scanning means located at predetermined locations along the length of the log.
Each scanning means includes a source 182 and a detector 184 arranged so that high-frequeney bursts o modulated, near infra-red light are pulsed from source 182 to detector 184. Examples of such scanners are Optimux Series 200 manufactured by Opcon, Inc.
The scanning means are provided to measure the distance from longitudinal axis 135 to a peripheral point on the log which "breaks" a scanning beam during rota~ion of the log. The sources and detectors are arranged so that data signals are fed into a computer.
As shown in Fig. 5, in functional block diagram form, a computer is operativeIy interconnected to the sources and detec-tors. Shaft encoders 50a, 96a and 144a also are coupled to the cornputer and generate data signals indicating the amount of shaft rotation of motors 50, 96 and 144. From this data, the computer can determine the position of reference point 70a relative to axis 28a as well as the position of the end of cylinder 88 along slide rod 110.
For purposes of clarity, motor 96 coupled with power transmission means 100 and slide mechanism 92 can be thought of as a so-ealled X-axis actua~or. Similarly, motor 50 coupled wi~h power transmission means 65 and rod 68 is referred to as a Y-axis actuator. The computer is programmed to always know the posi tions of the actuators and is also operable to generate signals for seIectively shifting the orientation of the actuators.
OPERATION OF THE SYST_ :
In order to prepare a log for optimum peeling on a veneer lathe according ~o the principles of the presen~ invention, the log is initially fed onto V members 178. Charger arms 134 12.

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are disposed in a substantially vertical or pre-spot position as shown in Fig. 2, and spindles 132 are retracted. V members 178, 180 are ~hen displaced toward each o-ther so that V member 180 contacts an upper surface of the log An approximate longitud~
inal center of the log is thereby defined by an axis extending through spindles 132 and reprPsented by line 135. Spindles 132 are then extended so that dogs 133 grip the log. at its opposite ends. As shown in Fig. 1, spindles 132 are engaged with a log, shown in dot-dash. A larger log is also illustrated merely to demonstrate that the system can accommodate various sized logs.
The log is no~ ready to be rotated through the scanning sys~em.
Encoders 134a on motors 144 feed a data signal into the computer indicating the relative position of a preselected point on spindles 132. The spindles are then driven by motors 144 so that the log is correspondingly rotated ~hrough 360. The encod-ers 134a are calibrated to indicate to the computer when rotation of predetermined arcs ~for example, 15~ ha~e been completed.
Correspondingly, the source and detectors are operatiYely connect-ed to the computer to indicate the distance from center 135 to a peripheral point during each 15~ rotation which "breaks" a beam between the source and detector. In this way, the computer receives information concerni~g the peripheral or surface config-uration of a log based upon the distance from axis 135 to outer beam-breaking points. It is to be noted that Figs. 1 and 2 indi-cate a scanning system utilizing three source detector pairs, but the number used will be determined by the accuracy desired for computing an optimum spin axis.
~ ith reference now directed to Figs. 3, 3a and 3b, an important feature of the present invention is to be noted. These figures illustrate one end, or a section of a log L, as the log i9 rotated through a portion of a scanning sequence. As shown in Fig. 3 J' as log L is rotated about axis 135, a peripheral point . , , 186 will break a scanning beam at the end of a particular 15 rotation. However, as can be seen from a consideration of Fig.
3a, other points 187~ 188 will also break another beam after another arc of rotation. The deepest concave part of log L will never be presented to face a beam. As shown in Fig. 3b, point 189 breaks a beam during another segment of the rotation. The result o this construction is that a surface configuration based on outer peripheral points rather than interior concave points will be developed. This information is then fed to the computer which determines a so-called optimum spin axis. The spin axis is the axis of a cylinder which will be included in the volume defined by the aforementioned non-concave peripheral points.
The importance of deterrnining a spin axis based upon an outer periphery can best be appreciated by considering Fig. 6.
A heart-shaped log Ll is illustrated having a concave region 190.
The scanning system just described will provide the computer with data from which a cylinder having an outer circumference repre-sented by 192 will be calculated. A spin axis 192a represents the longitudinal axis of such a cylinder. This is to be con-trasted from the previously mentioned reflector scanning systemwhich would take into account even the deepest regions of concave portion 190. Such a system would compute a cylinder 194 and a spin axis 194a. Circumference 194 is defined by the largest diameter which can be included within the peripheral boundary of log Ll.
Assuming that spin axis 194a is placed in the chucks of a veneer lathe, it can be seen that a veneer knife, schematically represented at 196, will initially peel small strips from log Ll until it reaches the circumference 194. Thereupon, longer, full length sheets will be peeled. However, if spin axis 192a were placed in the chucks of a veneer lathe, knife 196 would also initially peel small strips of veneer but would soon contact 1~.

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While such sheets ~ould not be continuous due to concave portion 190, such sheets would s~ill be considerably longer and more usable than the small strips which would be peeled off if spin axis 194a were used.
Thus, using spin axis 192a, it can be seen ~hat rela tîvely long sheets can be peeled from log Ll until the log is reduced in dimensions such that knife 196 can start to peel full length sheets. The non-full length sheets find utility as core material in plywood. It has been determined that the yield of usable veneer material utilizing a circumference developed as indicated by 192 with spin axis 192a will produce more usable veneer ~han an internal circumference such as represented by spin axis 194a. Thus, it can be appreciated that greater utilization of log material results.
It is to be noted that spin axis 192a, calculated as described above, will be o~fset from approximate a~is 135.
Points on either end of the log representing spin axis 192a will be offset differently from approximate axis 135. Thus, it is important, for reasons to be hereinafter described, that charging arms 34 be independently operable for proper placement of a computed spin axis in the veneer lathe.
After spin axis 192a has been calculated, the spin axis must be aligned on axis 198 which represents ~he axis through the chucks of a veneer lathe. As shown in Fig. 2, arm 34 is pivotal about pivot axis 28a of shaft 28. The ~ollowing description will describe how charger a~n 34 is moved to grip log L and move it so that spin axis 192a is aligned in lathe axis 198. It is to be remembered that each a~n 34 is operable independently of the other. In order to clarify the following description, reference must also be directed to Fig. 7- As shown in Fig. 2, arm 34 is initially positioned in the pre-spot position. Shaft encoder 50a 15.
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-~ 8 transmits data to the computer indicating the relative position of reference point 70a along radius arm 197 extending from pivot 28_.
As a first step, actua~ing means 86 is operated to retract rods 90 so that shoe 70 is positioned adjacen~ to spin axis 192a. It is preferable to position point 70a as close as possible to spin axis 192a, but close positioning may not be pos-sible beca~se of certain wood conditions providing a poor grip-ping surace. As s~own in Fig. 7, reference point 70a is posi-tioned somewhat away from spin axis 192a. It is to be noted tha~present charging apparatus are designed so that the distance between pivot axis 28a and axes 135, 198, are the same so that an arc 200 connects the axes. However, in the presen~ case, spin axis 192a is offset from axis 135 and thus, if moved to the same arc, would not be aligned with lathe axis 198. ~ccordingly, it can be seen that spin axis 192a must be shifted so as to be positioned on lathe axis 198.
After point 70a has been positioned adjacent to spin axis 192a, cylinders 116 are actuated so that rods 120 are re-tracted for engaging dogs 73 with an end of the log for securelygripping it. Spindles 132 are then retracted and actuating means 86 are operated to extend rod 90 to the right as shown in Fig. 2.
Charger arm 34 is then swung to the right. During this movement~
it is necessaxy to readjust axis 192a so that it will be aligned with lathe axis 198. This is accomplished by the aforementioned X and Y a2is actuators. Arm 34 is ~hown in approximately the middle of its swing in ~ig. 7, and spin axis 192_ must be moved a certain amount in the X and Y directions ln order to be posi-tioned on arc 200 for eventual placement aligned with lathe axis 198. The computer has calculated these distances and signals the respective actuators so that the appropriate X and Y axis adjust-ments are made during swinging movement. Thereupon, spln axis 16.

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192a is aligned on lathe axis 198. The chucks of the lathe then engage the ends of the log and rods 120 are extended to disengage dogs 73 ~rom the log. Char~er arm 34 is ~hen pivoted by means o~
actuating means 86 to the aforementioned prespot position.
From the above description and operation, it can be seen that the present invention provides several distinct advan-tages. For instance, the scanning system utilizes break beam scanners coupled with a computer for determining a spin axis which will yield the optimum amount of veneer. The spin axis is calculated based upon a nonconsideration of the innermost points of concave portions of a log so that a cylinder may be defined within the log and partially without. Thus, rather large, though not necessarily full-leng~h sheets of veneer may be peeled from the log which would not be obtainable if the spin axis were calculated based upon a right cylinder lying entirely within the log.
The present invention also provides X and Y actuators for selectively positioning pivotal charger arms so that a log having a predetermined spin axis may be positioned such tha~ the spin axis is aligned accurately within extremely close tolerances on the axis of the chucks of a veneer lathe. For instance, it has been determined that accuracy within 0.005 inches can be obtained with the present invention.
Furthermore, it is to be noted that existing charging apparatus may be readily modified according to the principles of the present invention. For instance, as shown in Fig. 1, beam 38 and tube 42 are illustrated as being separated alon~ their lengths, such separation permitting independent movement of the charger arms. The X axls actuator permits adjustment of actuat-ing m2ans 86. Prior to being modified with the X axis actuator,cylinder 88 could actuate rod 90 only between predetermined positions.

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,' Another advantage of the present invention resides in the use of ~xtendible retractable and rotatable spindle assem-blies 130. A relatively simple construction results in trouble-free and precise rotation and extension or retraction of spindle 132 within cylinder 134.
Wnlile the present invention has been described with reference to the foregoing pr,eferred,embodiment, it will be readily appreciated that other changes and modifications can be made by one having ordinary skill in the art.
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Claims (5)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An apparatus for scanning the surface configura-tion of a log and transferring the log so that a predetermined log spin axis is aligned in the chucks of a veneer lathe com-prising: a frame; rotating means mounted on said frame includ-ing a power-driven extendible-retractable spindle for rotating a log about a longitudinal axis; electro-optical scanning means disposed ajacent to said log and including source means for emitting beams of light across a rotating log to a detector means, said light beams being interrupted during continuous rotation by peripheral points on the log to thereby generate electrical signals indicating distances from said longitudinal axis to the interrupting peripheral points; computer means for receiving said signals and determining a spin axis based on said distances; shaft encoder means connected to said spindle for producing electrical signals to said computer means indica-ting the degree of rotation of said spindle; a pair of elongate charger arms pivotally connected to said frame including grip-ping means operable for gripping the ends of the log and transferring it to locate said spin axis in alignment in the chucks of the veneer lathe, said gripping means being mounted on a rod which is slidably mounted in a guide means provided on each arm; power-driven means mounted on each of said arms and power transmission means operatively coupled to said power-driven means and said gripping means for selectively extending and retracting said rod relative to said guide means in a direction generally along the longitudinal axis of said arm;
and actuating means provided for independently angularly dis-placing an associated arm, each of said actuating means being mounted on said frame and shiftable in a substantially horizon-tal direction.

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2. The apparatus of claim 1, wherein additional power-driven means are mounted on said frame adjacent to an associated actuating means, and wherein power transmission means are operatively coupled to said additional power-driven means and said actuating means for selectively shifting an end of said actuating means in a generally horizontal direction.

3. The apparatus of claim 2, wherein each of said power transmission means includes an elongate ball bearing screw mounted in a nut and movable in the direction of its longitudinal axis.

4. The apparatus of claim 3, wherein each of said actuating means is mounted on a slide mechanism, said mechanism being connected to an associated one of said screws and shift-able upon screw movement.

5. The apparatus of claim 4, wherein each of said power-driven means is provided with an encoder means for gener-ating electrical signals to said computer means indicating the position of its associated power transmission means, said encoder means also being operable to actuate said power-driven means.

20.