Apparatus For Cutting Lumber To Specified Clear Lengths

Abstract

A piece of lumber is fed flat to the infeed end of a marking station, tilted on edge and driven endwise into the marking station where defects in the piece are detected and marked with a retroreflective material. The marked piece moves to a defect-cutting station where it is driven endwise past a pair of defect-cutting saws until a marked defect is sensed between the saws to stop movement of the piece and actuate the saws to remove the defective section. The clear piece downstream of the saws is measured and, if longer than a minimum length range, diverted to a cut-to-length saw station. If within the minimum length range, it is diverted to a "core block" sort. If shorter than the minimum range, it is diverted to junk. The piece upstream of the saws is measured and diverted in the same manner as the downstream piece except that upstream pieces longer than the minimum length range resume travel past the defect saws. Long-length sensors at the defect station determine if a piece contains any one of several specified defect-free long lengths and if so, set a stop downstream of the defect saws corresponding to the longest specified clear length sensed and then actuate only one of the defect saws to cut the piece to such length when the piece reaches the set stop. Such piece is then diverted directly to a sorting station. Random length clear pieces transferred to the cut-to-length station are pressed against a series of depressible stop-sensors determining various specified lengths, driven endwise over the stop-sensors past a length saw until one of the stop-sensors is released, then driven in reverse against the released stop. The length saw then strokes to cut the piece to specified length, after which the piece is sorted according to length as determined by the released stop-sensor.

Parent Case Text

This application is a division of my prior co-pending application Ser. No. 214,011, filed Dec. 30, 1971, for Method and Apparatus for Cutting Lumber to Random or Specified Clear Lengths.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the cutting and sorting of lumber to random or specified clear lengths.

2. Description of the Prior Art

Heretofore the removal of defects from lumber and the cutting of the resulting clear pieces to one of several specified clear lengths with a minimum of waste has been largely a manual, trial-and-error operation. For example, in one typical prior system, each of ten saws manned by twenty people is equipped with a set of some twenty manually operated stops spaced at varying distances from the saw to determine various specified lengths. Each person takes a piece of lumber, inspects it, then using one of the saws cuts the piece on opposite sides of any defect to remove the defective section. Thereafter the same person places each resulting random length clear piece against a manually set one of the several steps estimated to be the one that will cut the longest specified clear length from such piece with a minimum of waste. However, if the operator errs in his estimate, he must clear the set stop and set other stops until the one stop is set that will produce the longest possible specified length from the piece. In practice, an operator must re-estimate and reset stops for a given piece approximately fifty percent of the time, thereby losing valuable production time. Thus as presently practised, the upgrading of low-grade defect-containing lumber by cutting it to specified clear lengths is a costly, time-consuming operation, particularly with the high labor costs involved.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for removing defects from lumber and cutting the lumber to random or specified clear lengths with a minimum of labor and at a high rate of production exceeding that possible with the aforementioned prior method. The invention eliminates the human guesswork and trial-and-error estimation of the longest specified clear length in a given piece of lumber involved with the prior method. The invention also eliminates the manual setting and resetting of stops.

A basic feature of the invention is the separation of the defect- and length-cutting operation into two separate steps, including a defect-cutting step carried out at a first cutting station and a cut-to-length step carried out at a subsequent cutting station.

A further basic feature of the invention is the use of each individual piece of lumber to carry its own information necessary to trigger various machine operations in proper sequence, thereby eliminating the need for costly computer or memory systems to operate the apparatus.

Another feature of the present invention is a built-in sorting system which sorts pieces according to length from length sensings made at the defect- and length-cutting apparatus.

According to another feature of the invention, various specified clear lengths in a board are sensed automatically and these sensings used to operate various elements of the apparatus as required to position the board for cutting, to cut the board to a specified length and to sort pieces according to length.

A more specific feature of the invention is the marking of defects in a board with a retroreflective material which can be sensed to initiate machine functions which either remove the defect from the board or cut the board to a specified long clear length.

In another specific aspect of the invention, boards containing at least one of several specified long, clear lengths can be detected, positioned and cut automatically to the longest possible one of the specified lengths at the defect-cutting station and then diverted to a corresponding sorting station without passing through the cut-to-length station.

A prototype apparatus of the invention is designed to process 15,000 board feet per day using from one to three persons, thereby giving a production rate per person of from 5,000 to 15,000 board feet. This should be compared to the 1,500 board feet per person capable of being produced using the typical prior system previously described.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description which proceeds with reference to the accompanying drawings, wherein:

FIG. 1 is a plan view of an overall system in accordance with the invention;

FIG. 2 is a vertical sectional view on an enlarged scale taken approximately along the line 2--2 of FIG. 1 showing the infeed end portion of the apparatus of FIG. 1;

FIG. 3 is a vertical section taken approximately along the line 3--3 of FIG. 1 showing the details of the marking station portion of the apparatus;

FIG. 4 is a view taken along the line 4--4 of FIG. 3 showing an infeed portion of the marking station in plan;

FIG. 5 is a plan view of the sorting section of the apparatus of FIG. 1;

FIG. 5A is a continuation of FIG. 5 showing a plan view of an outfeed portion of the defect-cutting station;

FIG. 6 is a view taken approximately along the line 6--6 of FIG. 5 showing the sawing and sorting sections of the apparatus in elevation;

FIG. 7 is a plan view of the cut-to-length station as viewed along the line 7--7 of FIG. 6 rotated to a horizontal plane and with other portions of the apparatus removed for clarity;

FIG. 8 is a partial sectional view taken along the line 8--8 of FIG. 7 on an enlarged scale;

FIG. 9 is a sectional view taken along the line 9--9 of FIG. 7 on an enlarged scale;

FIG. 10 is a view taken along the line 10--10 of FIG. 5-A showing one of the pop-out stops;

FIG. 11 is a view taken along the line 11--11 of FIG. 9 showing one of the stop-sensors;

FIG. 12 is a circuit diagram of the electrical sensing and control system of the apparatus;

FIG. 13 is a circuit diagram of the pneumatic-fluidic sensing and control system of the apparatus; and

FIG. 14 is a diagram of a manual control stick portion of the control system.

DETAILED DESCRIPTION

GENERAL ASSEMBLY

With reference to the drawings, FIG. 1 shows the overall apparatus, including an infeed section 10, a marking station 12 just downstream from the infeed section where defects are marked, and an operator's station 14 alongside the marking station. A transfer section 16 transfers marked lumber from the marking station 12 to a cutting and sorting section 18. At the cutting and sorting section, marked defects are first detected and cut from pieces at a defect-cutting station 20 after which the resulting random-length clear pieces are dropped to a cut-to-length station 22 and then to a sorting section 24 where the pieces are sorted to length.

INFEED SECTION

Referring to FIGS. 1 and 2, pieces from a stack of lumber 26 on a scissors lift 27 at the head of the infeed section are fed onto a declining skate wheel section 28 leading to a zero trim table 30. Pieces roll down the skate wheels 28 onto a series of driven ending rolls 32 which drive the pieces endwise against an ending bumper 34. Lug chains 36 push one piece at a time from the ending rolls through a zero trim saw 38 and onto a declining skidway comprising a series of skid rails 40. Each piece P slides down the rails in a flat condition to a stop 42 at the bottom of the skidway. As each piece arrives at the stop, it has its right-hand end as viewed in FIG. 1 referenced in the same position as every other piece with respect to the infeed end of the marking station 12 regardless of the length of the piece because of the zero-referencing action of the zero trim table.

At the lower end of the skidway, means are provided for turning each board on edge and for flipping it completely over. Such means includes a flipper arm assembly comprising a series of flipper arms 44 mounted at spaced intervals along a common shaft 46. As clearly shown in FIG. 2, the flipper arms in their inactive positions lie below a piece of lumber P at the bottom of the skid rails. The flipper arm assembly is actuated by a tandem pair of air cylinders 47, 48 pivoted to the frame of the machine at 49 and pivoted at 50 to a crank arm 51 of shaft 46. Upon extension of cylinder 47, arm 44 pivots to an inclined position 44a to lift a piece P on edge as shown. Upon extension of both cylinders 47, 48, arm 44 is pivoted to a near vertical position 44b to flip a piece P completely over to its opposite face. The flipper assembly is controlled from the operator's station 14. There the operator, positioned in a seat 53 on a platform 54, overlooks the flipper assembly and can flip a given board so that its most defective face will be tilted toward the operator as it passes through the marking station 12.

If desired, the zero trim table can be eliminated and additional skate wheels or other means provided for feeding pieces of lumber manually one at a time onto the skid rails 40 for manipulation by the flipper arms.

Lumber from stack 26 can be fed automatically to the skate wheels using automatic lumber feeder devices common in the industry. Alternatively, a second person can be stationed at the stack on an extension 55 of the operator's platform and can manually feed one piece at a time from the stack 26 to the skate wheels.

MARKING STATION

When a piece of lumber arrives at the bottom of the skid rails and is tilted on edge at approximately a 60.degree. angle to the horizontal by the flippers as shown in FIG. 3, its righthand end as viewed in FIGS. 1 and 4 is supported by a wear plate 58 and the driven roll 60 of a pair of nip rolls at the infeed end of the marking station. The infeed nip rolls also include an idler roll 61 movable toward and away from the driven roll by an air cylinder 62. Nip roll 60 is driven by a reversible orbit motor 64. Idler roll 61 is carried on an arm 65 pivoted at 66 to a support 67. Wear plate 58 is downturned at its opposite ends as shown at infeed end 68 to prevent boards from hanging up on the plate. The wear plate forms part of an angle member 69 and also includes a fence portion 70 providing support for a back portion of a piece of lumber traveling along the wear plate.

The wear plate defines a linear path of travel for a piece of lumber P driven endwise through the marking station by the infeed nip rolls. The speed and direction of endwise travel of a piece through the marking station is controlled from the operator's station by controlling the speed and direction of rotation of motor 64.

A marking means shown most clearly in FIG. 3 is provided at the marking station along the path of travel of a piece The marking means includes a spray nozzle 72 directed toward the face of any board passing through the marking station. The nozzle is supplied with a fast-drying retroreflective liquid from a reservoir (not shown) which is sprayed under control of the operator onto defects, such as knots, detected in a board as it travels on edge through the marking station. Defects marked in this manner are detected later by photosensors which actuate saws that remove such defects. A defect can readily be aligned with the marking nozzle 72, which is preferably directly in front of the operator as shown in FIG. 1, by reason of the reversible and variable speed drive provided for the board.

The marking station also includes an outfeed means comprising a pair of outfeed nip rolls 74, 75 similar in arrangement and operation to the infeed nip rolls 60, 61.

The opening and closing of both the infeed and the outfeed nip rolls are controlled automatically by photoelectric sensors shown schematically in FIG. 1 including an infeed sensor PC-1 and an outfeed sensor PC-2. The infeed sensor detects the presence of a board in position at the infeed end of the marking station and in response to such sensing closes the normally open infeed nip rolls, driving the lumber into the marking station. When the leading end of the lumber passes outfeed sensor PC-2, the outfeed nip rolls close enabling the lumber to be driven out of the marking station and onto the aligned end of the transfer section 16.

When a board moving through the marking station clears the infeed rolls 60, 61, sensor PC-1 causes such nip rolls to reopen to await delivery of the next board. Similarly, when the trailing end of the same board clears the outfeed nip roll sensor PC-2, the outfeed nip rolls reopen to await the next piece.

TRANSFER SECTION

Transfer section 16 includes a series of screw rolls 80 mounted on a frame table 82. The rolls are rotated by a chain drive 84 in a direction so that lumber fed to the ends of the rolls in alignment with the marking station will be conveyed both downstream and sideways to the opposite ends of the rolls and up against a fence 86. The fence serves to align each board endwise with the infeed end of the defect-cutting station. An angled bumper plate 88 limits the downstream movement of a board on the transfer table. Such plate also guides the leading end of each board toward a gate 94 and a pair of normally open nip rolls 90 at the infeed end of the defect-cutting station, as shown most clearly in FIG. 5. Nip rolls 90 are similar to the nip rolls previously described and include an air cylinder-actuated upper idler nip roll and an orbital motor driven lower nip roll, the air cylinder being shown at 91 and the orbit motor at 92.

Gate 94 is bounded on one side by a short fence section 96 and on the opposite side by a gate idler wheel 98 on bumper 88. The lower portion of the gate is defined partially by another idler wheel 99. Gate idler 98 is pivoted at 100 to a slide plate 102 and spring-biased toward the gate opening to prevent boards from moving through the opening until they are positively driven by nip rolls 90. Slide plate 102 is slidably adjustable along the upper surface of bumper 88 to adjust the size of the gate opening to accomodate various board widths.

Referring to FIG. 5, each screw roll 80 has two annular ribs 80a at its infeed end. These ribs prevent sidewise movement of the leading end of a board as it is fed onto the screw rolls by the outfeed nip rolls at the marking station until the entire board clears the outfeed nip rolls. When this happens, the edge-tilted board falls flat on the screw rolls enabling the helical ribs to begin their sideways conveying movement of the board toward fence 86.

A photoelectric sensor PC-3 at the infeed end of the transfer table senses the presence of a board on the table. This sensor illuminates a red warning light on a control panel at the operator's station if the sensor remains activated too long, indicating a full table.

Another sensor PC-6 near gate 94 senses the presence of a board at the gate and between nip rolls 90 to close such rolls, enabling the infeed of a board into the defect station.

DEFECT-CUTTING STATION

The details of the defect-cutting station are shown most clearly in FIGS. 5, 5-A and 6. The relative levels of the defect-cutting station, screw roll transfer section 16 and cut-to-length station 22 with respect to floor level and each other are shown in FIG. 6. The defect-cutting station is supported on a structural framework indicated generally at 104 which includes longitudinal channel members 106, 108 supporting the defectcutting means and its actuating mechanism and pairs of longitudinal and vertically stacked rectangular tube members 109, 110 supporting the other components of the defect-cutting station. All of these longitudinal frame members extend between and are supported by cross frame members 112, 114.

A pair of parallel, longitudinally extending fence assemblies, one fixed and one laterally movable, define a linear, horizontal path of travel for lumber fed endwise into and through the defect-cutting station. The fixed fence assembly includes a short fixed fence 116 and a longer fixed fence 118, both defining continuations of the fence 86 of the transfer section and the short fence 96 of the gate leading into the defect station. The movable fence assembly includes a short movable fence 120 in opposition to the short fixed fence and a long movable fence 122 opposite the long fixed fence 118.

The short movable and fixed fence sections are suspended beneath fence supports 124, 125. The long fixed and movable fence sections are supported from similar fence supports 126, 127 and 128. All of these fence supports are longitudinally slotted as shown at 129 on support 127 to receive suitable fasteners and to serve as slideways for the movable fence sections. The fence supports in turn are fixed to the tubular longitudinal frame members 109, 110. Air cylinders 132 fixed to the underside of fence supports 124, 125, 126 and 128 are connected also to the movable fence sections for moving such sections in unison toward and away from the fixed fence sections.

As shown best in FIG. 6 with respect to short fixed fence 116 and short movable fence 120, all fence sections carry bottom plates 134, 136 which have lip portions extending inwardly beyond the fence members themselves to form a drop gate which either supports a board within the defect station or drops a board from it, depending on the position of the movable fences. The plate 136 on the fixed gate sections is downturned at its outer end so as to guide a board downwardly along an inclined slideway when the movable fence is retracted by cylinder 132 to release the board.

The defect-cutting means includes a pair of defect-cutting circular saws 138, 139 positioned as shown in FIG. 5 in a gap between the short and long fence sections. Saw 139 is mounted on a fixed base 140. However, saw 138 is mounted on an adjustable base 141 which enables the spacing between the pair of saws to be adjusted within the range of a few inches, with such range, for example, normally being approximately four to six inches. Except for the adjustable nature of the base of the movable saw, the mounting and actuation of the two saws is identical and so will be described only for the movable saw.

Saw 138 is fixed to a driven shaft 142 rotatably mounted on a yoke arm 144. The yoke arm is pivoted to base 141 at 145. The yoke arm carries a pulley wheel 146. A drive belt 148 interconnects the yoke arm pulley and a driven pulley 150 connected to the drive shaft of an electric motor 152 for driving the saw. The motor is mounted on a base plate 153 which is pivoted at 154 to the main base 141.

The saw-actuating means includes a toggle mechanism 156 pivoted at one end to an overhead frame member 157, at the other end to the yoke arm 144 and in the center to an air cylinder 158 which in turn is connected to an upright frame member 159. Thus in the normal inactive, retracted position of the saw, air cylinder 158 is retracted to position the lower cutting edge of the saw above the level of a board P supported between the fixed and movable fences. However, upon extension of the air cylinder, the toggle mechanism forces the yoke arm 144 downwardly and then upwardly, thereby moving saw 138 through its cutting stroke to sever a board extending through the saw's cutting plane. Normally both the defect-cutting saws are actuated simultaneously to cut a short defective section from a board. The severed section then drops through the gap between fences to a "junk" collection point. However, for a reason to be developed later, each saw is also capable of operating independently of the other.

The means for driving pieces through the defect station comprises a pair of relatively fixed driver rolls 162 and an opposing pair of relatively movable idler rolls 164 mounted on opposite sides of the pair of defect saws just inwardly toward the saws from adjacent ends of the fixed and movable fence sections. Idler rolls 164 are carried by the movable fence sections so as to move with them. Driver rolls 162 are carried by the fixed fence sections. They are spring-loaded to extend a short distance beyond the lumber-engaging edge of these fence sections. The idler rolls are spring-loaded to extend a slightly greater distance beyond the lumber-confronting edge of the movable fence sections. Thus when the opposing spring-loaded drive and idler rolls press against the opposite edges of a piece of lumber within the defect-cutting station, they apply unequal forces against opposing edges of the lumber in a manner resulting in the lumber being held against the fixed fences with a positive force. This ensures that the drivers will firmly engage the lumber to drive it through the defect station while at the same time the lumber will follow a true straight course as defined by the fixed fence. The driver rolls are driven by orbital motors 166 depending beneath the rolls, one such motor being shown in FIG. 6.

The defect saws are covered by a removable overhead guard 168. The overhead guard also mounts a bracket 170 to which four photoelectric sensors I-5, I-10, O-5, O-10 are mounted. These photoelectric sensors and others are illustrated elsewhere schematically by triangular symbols for simplicity and clarity. Actually these sensors and others may be mounted anywhere on the apparatus where convenient. A fifth photosensor PC-4 is mounted behind and between the pair of defect saws on an upright support member 176 to detect defects between the saws. The functions of these and other sensors are described subsequently.

Referring to FIG. 5-A, fixed fence 118 ends a shorter distance downstream of the defect saws than corresponding movable fence 122. A stop bar 178 continues downstream from the downstream end of the fixed fence. Three air-actuated pop-out mechanical stops 180, 181, 182 are pinned to the stop bar at predetermined but adjustable positions along it to determine the downstream ends of three specified long clear lengths which can be cut from a piece using one of the two defect saws. In conjunction with these mechanical stops, three end-of-piece photo sensors A-1, A-2, A-3 are positioned along the stop bar upstream of the stops and operate in conjunction with a defect sensor PC-5 upstream of the defect saws. A second set of three photoelectric end-of-piece sensors SA-1, SA-2, SA-3 are positioned on the stop bar, one just in front of each pop-out stop to slow the drive rolls before a board reaches such stops. Finally a maximum length mechanical stop-sensor 188 is adjustably positioned on the stop bar downstream of the pop-out stops to stop and control the processing of any piece that is not acted upon by the pop-out stops and has no defect detected prior to reaching such stop.

FIG. 10 shows one of the pop-out stops in detail. This typical pop-out stop includes a stop body 190 adjustably connected to stop bar 178 by a pair of removable pins 191 extending through a pair of openings 192 in the stop body and through an aligned pair of stop bar openings 193. An upwardly extending portion 194 of the stop body pivotally mounts an air cylinder 195 via pivot pin 196. The air cylinder has a piston rod portion 197 pivotally connected at 198 to a pop-out stop lever 199. The stop lever is pivoted to the stop body at 200. Thus when the air cylinder extends, the piston rod 197 pivots stop lever 199 downwardly and outwardly to a horizontal position 199a in the path of lumber passing downstream through the defect station.

Referring to FIG. 6, the defect-cutting station includes an associated sorting and transfer means. Such means includes inclined slideways 202, 204 which merge at their upper ends at a primary diverter or flip-flop gate 106. This gate determines onto which slideway a piece will drop when released from the defect-cutting station through retraction of the movable fence sections.

The transfer slideway 202 leads to cut-to-length station 22. The sorting slideway 204 leads to a series of sorting stations to which pieces from the defect station are directed according to length or condition without passing them through the cut-to-length station. Sorting slideway 204 includes a pair of sorting gates 208, 209 leading respectively when open to conveyor belts 210, 211. Pieces sliding down the slideway 204 with both diverter gates 208 and 209 closed will proceed onto a third, transfer belt 212. Thus, for example, defective sections cut from a piece can be diverted to a junk sort by belt 210 by positioning flip-flop arm 206 in its right-hand position and gate 208 in its open position. Similarly, clear pieces too short to be dropped to the cut-to-length station can be diverted to a "core block" sort on belt 211 by keeping gate 208 closed but opening gate 209. As a further example, long clear pieces cut to length at the defect station can be diverted directly to a sorting station without passing to the cut-to-length station by positioning flip-flop gate 206 in its right-hand position and by closing gates 208 and 209 so that the long clear pieces drop onto transfer belts 212.

OPERATION AT DEFECT STATION

Summarizing the processing of lumber at the defect station, screw transfer rolls 80 crowd a piece of lumber with marked defects against fixed fence 86. When the defect infeed nip rolls 90 are clear of the preceding piece and piece-present sensor PC-6 detects the presence of a piece at the fence 86 and between nip rolls 90, the nip rolls close, feeding lumber endwise through gate 94 and toward defect saws 138, 139. At the same time movable fence sections 120 and 122 move inwardly to support the piece as it travels downstream in the defect station and to press the piece against the fixed fence sections and drive rolls 162. When photoelectric sensor PC-4 detects a marked defect on the piece between the saws, a signal from the sensor stops drive rolls 162 and the driven nip roll 90 and extends air cylinders 158 to stroke defect saws 138, 139 simultaneously to cut the defective section from the piece. This defective section drops from between the saws along slideway 204 through open gate 208 onto belt 210 where it is conveyed to the junk sort.

The remaining clear piece downstream of the defect saws is measured by a pair of outfeed photo sensors spaced apart a short distance downstream of the saw 139 including a junk sensor O-5 and a core block sensor O-10. If such downstream piece is longer than, say, 10 inches, it is diverted to the cut-to-length saw station. If such piece is within the range of, say, from 5 to 10 inches in length or as otherwise determined by spacing between the two sensors, it is diverted to the core block sorting station by opening gate 209. If shorter than 5 inches or any other predetermined minimum length as determined by sensor O-5, such piece is diverted to junk via open gate 208.

An identical pair of infeed sensors, including a junk sensor I-5 and a core block sensor I-10, measure and divert the remaining piece upstream of the saws in the same manner as the outfeed sensors except that upstream pieces longer than 10 inches or some other predetermined length resume their travel downstream toward the defect saws for processing as previously described through reactivation of nip rolls 90 and drive rolls 162.

A piece having an exceptionally long clear length as measured from its leading end can be cut to one of three specified long lengths at the defect-cutting station, thereby eliminating the need to transfer such pieces to the cut-to-length station, and enabling direct sorting of these pieces from the defect station.

Whether or not a given piece contains a clear length at least as great as one of the three specified long clear lengths is determined by defect sensor PC5 upstream of the defect saws and by the three end-of-piece sensors A-1, A-2, A-3 downstream of the saws. For example, if a piece moving past the defect saws has its leading end sensed by sensor A-1 but not sensor A-2 and A-3 as defect sensor PC-5 detects a defect, the associated electrical control circuit causes the air cylinder of pop-out stop 180 to extend and set such stop to block downstream travel of the piece when it reaches such stop. As the piece approaches stop 180, sensor SA-1 slows drive rolls 162 and nip roll 90. When the leading end of the piece reaches set stop 180, the drive rolls stop and only the second defect saw 139 strokes to cut the piece to the shortest one of the three specified long lengths. The movable fences retract and the gates are set to drop the long clear piece onto belt 212 to convey it to a long length sorting station, bypassing the cut-to-length station.

In a similar manner the activation of sensor PC-5 and both A-1 and A-2 would set stop 181, and the activation of sensor PC-5 with all three stops A-1, A-2, A-3 would set stop 182. The end-of-piece sensors and their corresponding stops can be adjusted to various positions along the stop bar to provide various specified long lengths. Also a fewer or greater number of pop-out stops and corresponding sensors could be provided as desired to meet the needs of the user.

CUT-TO-LENGTH STATION

As shown in FIG. 6, cut-to-length station 22 is positioned below and to one side of the defect-cutting station. As previously mentioned, pieces cut to random clear lengths at the defect station are dropped along slideway 202 to the cut-to-length station.

A piece arriving at the cut-to-length station is supported at about a 45.degree. inclination to the horizontal and on edge by lumber support means including a pivotable bottom drop gate member 224 and a movable side-supporting fence 226. As shown in FIG. 7, gate 224 is composed of three gate sections 224a, 224b, 224c mounted for downwardly pivoting movement on a common shaft 230 (FIG. 9). The fence and drop gate position a piece delivered to the cut-to-length station in parallel relationship to the position it occupied at the defect-cutting station. As shown best in FIGS. 8 and 9, the sections of drop gate 224 are fixed to long lengths of tubing 229 pinned to common shaft 230. The shaft is pivotally mounted in three sleeve bearings 228 having supports 227 attached to a frame portion 231 of the machine. The drop gate sections are pivoted downwardly simultaneously from a lumber-supporting position as shown in FIG. 8 to a position dropping lumber to the sorting area by an air cylinder 232 pivotally connected to a drop gate actuating arm 233.

A cut-to-length saw 234 is positioned along drop gate 224 and has a cutting plane 234a extending normal to the length of the drop gate in the gap between the drop gate sections 224a and 224b. With reference to FIG. 5, it will be seen that length saw 234 is in substantial alignment with the downstream saw 139. However, the cut-to-length saw is offset just slightly downstream from such defect saw so that random lengths dropping laterally to the cut-to-length station from the defect station will have one end extending slightly into the cutting plane of length saw 234.

Cut-to-length saw blade 234 is fixed to a shaft 235 carried on the outer end of a yoke arm 236. The yoke arm is pivoted at its inner end at 237 to a support base 238. The pulley 239 fixed on shaft 235 is driven by drive belt 240 from a second pulley 241 on the drive shaft of an electric motor 242. Yoke arm 236 pivots upwardly to move the cut-to-length saw through its cutting stroke by an air cylinder 244 acting on a toggle linkage 246. The cutting stroke of the saw is indicated by dashed lines in FIG. 6.

Two pairs of nip-drive rolls, including two inwardly movable idler rolls 248 on fence 226, an opposing fixed idler roll 249, and a single fixed driven roll 250 are positioned along drop gate 224 for moving a piece at the cut-to-length station endwise toward and away from the cut-to-length saw. The driven roll 250 is driven by an orbital motor 251 mounted on a support above the drive roll as shown in FIGS. 6 and 8.

A piece P dropped from the defect station to the cut-to-length station and supported on drop gate 224 is pressed against the fixed drive rolls 249, 250 by idler rolls 248 which move inwardly to engage one side of the piece with movable fence 226 under the influence of air cylinders (not shown). Drive motor 251 is reversible so that a piece can be driven in either direction along the drop gate, either toward or away from the cut-to-length saw.

A stop-sensor bar 254, shown in FIGS. 7 and 9, is positioned downstream of the cut-to-length saw opposite fence 226 and along drop gate sections 224b and 224c. The stop bar 254 is mounted on frame member 231. A portion of the stop bar overhangs the drop gate and is provided with a series of spaced-apart pin openings which provide for adjustable connection of a series of stop-sensors SS at various distances from the saw 234 so as to determine specified lengths to which random-length pieces will be cut by such saw. The stop bar also adjustably mounts a piece-present sensor PP which detects the presence of a piece of lumber at the cut-to-length station to trigger the actuation of the nip-drive rolls. One or more random-length sensors RS may also be mounted on the stop bar to drop certain long random-length pieces from the cut-to-length station without cutting them to length.

The stop-sensors SS are adjustably secured to stop bar 254 by a pair of removable pins 257 extending through aligned pin openings in the stop bar and stop-sensor. Referring to FIG. 11, the stop-sensor includes a stop body 260 having an upper groove 261 receiving a depressible stop lever 262. The stop lever is pivoted at 263 to the stop body and is biased outwardly by a spring 264 against the force of which the stop lever is depressible inwardly by a board forced against the stop bar. The lower portion of the stop body includes a pair of pin openings 265 which receive pins 257 for attaching the stop-sensor at the stop bar. For this purpose the lower portion of the stop body includes a groove 266 into which the stop bar projects.

Stop body 260 also includes an air tube connector 269 for connecting an air tube from a pneumatic-fluidic control panel (not shown). The connector leads into a drilled opening 267 in the body which connects to an air outlet 268 leading into the upper groove 261 of the body. Air entering the stop body is normally blocked by the stop lever 262 when in its normal released position. Thus normally the connected air tube will have a high back pressure. However, when the lever is depressed by a piece of lumber, air can escape through outlet 268, producing a low pressure in the connected air tube. However, when the stop lever is again released, this will again block the escape of air from the stop body, sending a pulse of high-pressure air to the pneumatic-fluidic control circuit for a purpose to be described in conjunction with FIG. 13.

The piece-present sensor PP and random-length sensor RS may be similar in construction to the stop-sensor, except that in the former the stop lever and associated outer groove are eliminated and the air tube connector communicates with an air outlet passage extending completely through the sensor body to its lumber-engaging surface.

Below the cut-to-length station there is another sorting area (FIG. 6) where boards cut to length by the length saw are sorted according to length. The sorting area includes two inclined slideways 270, 272. Slideway 270 includes a series of four diverter gates 274 selectively pivotable upwardly on shafts 275 by air cylinders (not shown) to divert boards into one of four chutes or bins 276. Each chute leads to one of two driven side transfer belts 278, 279, which, when the machine is in operation, continuously convey sorted material from the apparatus. The sorting chutes are constructed in pairs, with each pair being formed by two outer walls 280, 281 and a vertical divider wall 282. An additional series of end transfer belts 284 convey pieces not diverted into one of the four chutes from the apparatus. The four gates 274 include a random sorting gate 274a, a No. 1 sorting gate 274b, a No. 2 sorting gate 274c, and a No. 3 sorting gate 274d.

Slideway 272 includes a "junk" gate 286 and a "core block" gate 288. Each of these gates is upstream of the cut-to-length saw, whereas the sorting gates 274 are downstream of such saw.

OPERATION AT CUT-TO-LENGTH STATION

In operation a random-length clear piece of lumber from the defect-cutting station longer than the minimum length of, say, 10 inches drops along slideway 202 onto closed drop gate 224 with one end in alignment with the cut-to-length saw. Piece-present sensor PP detects the piece and closes the drive-nip rolls, causing the rolls and fence 226 to press one face of the piece against driven roll 250 and stop-sensors on bar 254, depressing some or all of the stop-sensors, depending on the length of the piece. When this occurs, drive roll 250 rotates in a counterclockwise direction, driving the piece endwise toward the cut-to-length saw. The piece continues toward such saw until the first one of the depressed stop sensors SS is released. Upon such release, drive roll 250 reverses to drive the downstream end of the piece against the released stop. Then air cylinder 244 extends to stroke the length saw 234, cutting the piece to a specified length as determined by the released stop. Air cylinder 232 then retracts, opening drop gate 224 and dropping the piece of specified length into one of sorting chutes 276. The chute into which the piece is diverted is determined by the released stop SS which, as soon as released, signals one of gates 274 to open through the pneumatic-fluidic control circuit of FIG. 13.

A pair of sensors upstream of the cut-to-length saw, including a junk sensor S-5 and a core block sensor S-10, determine the length of the short piece on that side of the saw. Pieces less than a minimum length of, say, 5 inches are diverted to junk through gate 286, whereas pieces between the minimum length and, say, 10 inches are diverted to the core block sort through diverter gate 288.

If a piece arriving at the cut-to-length station is less than the shortest specified length as determined by the position of the closest stop sensor SS-15 to the length saw, then piece-present sensor PP acts through the fluidic circuit to divert such short random-length piece directly to the random sort through gate 274a without stroking the saw. Additional adjustable random-length sensors such as sensor RS can be mounted on the stop-sensor bar to cause lumber covering such stops but not stop-sensors beyond such stops to be diverted to the random sort without saw operation.

The sensors on the stop-sensor bar are adjustable in short increments of, say, one-fourth inch. Each stop-sensor SS can be connected to field-changeable connections in the pneumatic-fluidic control circuit in such a way as to cause any selected one of the sorting gates 274 to open when a given stop-sensor is released.

CONTROL SYSTEMS

The control system of the illustrated embodiment is broken down into two parts. First, an electrical control system shown in FIG. 12 controls the operation of the marking and defect-sawing sections of the apparatus. Second, a pneumatic-fluidic control system shown in FIG. 13 controls the operation of the cut-to-length section and sorting therefrom.

ELECTRICAL CONTROL SYSTEM

Referring to the electrical control circuitry of FIG. 12, the portion of the circuit within bracket 300 represents marking station operations controlled manually from operator's station 14. This portion of the circuit includes a series of manually controlled switches including a "flip" switch 290, a "center" switch 291, a "down" switch 292, and a "feed" switch 293. These four switches are opened and closed selectively by the operator using a four-way "wobble" stick control 302 shown schematically in FIG. 14. With this stick the operator controls actuation of flipper arms 44 at the infeed side of the marking station and operation of the driven infeed nip roll 61. More specifically, with the wobble stick in its "down" position, arms 44 assume their retracted near-horizontal position as shown in full lines in FIG. 2. With the wobble stick moved to its centered position, flipper arms 44 pivot to their midway position 44a of FIG. 2 to tilt a board on-edge at approximately a 60.degree. angle to the horizontal. When the wobble stick moves to its "flip" position, flipper arms 44 pivot to their near-vertical position 44b in FIG. 2 to turn a board over on skid rails 40. When the desired face of a board is tilted toward the operator, movement of the wobble stick to its "feed" position activates the driven infeed nip roll 60 at the marking station to feed a board toward marking nozzle 72. In the illustrated circuit, the fifth position of the wobble stick is not used but could be used if desired to activate the infeed drive 60 in a reverse direction to help center a defect at the marking nozzle 72.

Time delay relay TDB in line 294 controls the time interval between commanding the flipper arms to their down position and their return to their centered position 44a by closing contact TDB in line 295. When "flip" is commanded by the wobble stick, flip switch 290 moves downwardly to close lines 296, 297, thereby extending both air cylinders 47 and 48 in FIG. 2. With the wobble stick centered, "center" switch 291 closes in line 295, and as soon as relay TDB times out, its contact TDB in line 295 also closes, thereby extending only air cylinder 47 to move flipper arms 44 to their midway positions 44a. With the wobble stick in the "down" position, lines 304 and 304a are closed by upper throw of switch 292 to retract cylinders 47 and 48 and return flipper arms 44 to their lowered positions.

A relay X in line 306a is a control relay which allows the infeed nip rolls 60, 61 to remain closed if a piece of lumber is present between such rolls and "feed" is commanded by the wobble stick. Sensor PC-1 is a retroreflective photocell which senses lumber in the marking station infeed nip rolls and in response closes a normally open contact PC-1 in line 306 to retract air cylinder 62 and thereby close the nip rolls. A spring return on cylinder 62 opens the infeed nip rolls when contact PC-1 is reopened by the absence of a piece between such rolls.

Retroreflective photocell PC-2 at the outfeed nip rolls 74, 75 of the marking station closes a corresponding contact PC-2 in line 308 when a piece is present between such rolls, thereby actuating an air cylinder to close the outfeed nip rolls. The outfeed nip rolls reopen via a spring return when a piece is no longer present between such rolls.

A retroreflective photocell PC-3 on the screw roll transfer table senses the presence of lumber on such table and closes a corresponding contact PC-3 in line 310 to energize a time delay relay TD-1. This relay times out if photocell PC-3 is blocked longer than its setting to close relay contact TD-1 in line 310a and thereby illuminate a warning light R on the operator control panel to warn the operator that the transfer table is full.

Photocell PC-4 is a retroreflective "line scan" photocell which senses a marked defect between the defect saws. When a defect is sensed, corresponding contacts PC-4 in lines 312, 315 close to energize single coil latching relays L-1 and L-2. These relays close corresponding contacts L-1 and L-2 in lines 313, 316 to extend the air cylinders 158 for the defect saws to stroke such saws simultaneously. Normally closed latching relay contacts L-1 and L-2 in lines 314, 317 retract the defect saw actuating cylinders to return the saws to their initial positions.

The portion of the circuit within bracket 318 represents an anticipator circuit which provides the control for cutting pieces to specified long clear lengths at the defectcutting station. This circuit includes a permanent magnet latch relay PML in line 319. A pulse through line 319a causes unlatching of the relay, whereas a pulse through line 319b causes latching of the relay. The relay latches if the anticipator system is to be used. In this regard a pulse from photocell PC-4 closes a corresponding contact PC-4 in line 319a to cause unlatching of the relay. On the other hand, a pulse from the retroreflective line scan photocell PC-5 upstream from the defect saws closes a contact PC-5 in line 319b to cause latching of the relay when it senses a marked defect. This photocell is also used to control the screw roll transfer table off-feed nip rolls 90, although a separate photosensor PC-6 also serves this function.

A limit switch SW-1 senses lumber at the defect saw outfeed drive roll. It has a contact SW-1 in line 319c in parallel with a normally open contact PC-4 in line 319a which functions to control the resetting of relay PML. An additional switch contact SW-1 in line 323b controls a relay KA in line 323 which stops the motor for drive rolls 162 by closing contact KA in line 327. A third contact SW-1 in line 338a energizes time delay relay TD-4 in line 338. This relay controls the time allowed for the defect saws to stroke by delaying the retraction of the movable fence to drop a clear piece until after it times out to close relay contact TD-4 in line 340.

Sensors A-1, A-2 and A-3 are retroreflective photocells positioned on the outfeed side of the defect saws and at adjustable distances therefrom for sensing the downstream end of a piece traveling downstream through the defect station. These three sensors determine the maximum length available for the long clear cut-to-length function of the defect station. Latching of the PML relay in line 319 by photocell PC-5 closes a contact PML in line 326, energizing a time delay relay TDA forming part of a "one-shot" system for the anticipator circuit. The closing of the PML contact also energizes a control relay C in line 326a, in parallel with the relay TDA. Relay C is an output control for the one-shot anticipator system and remains energized until relay TDA times out to open contact TDA in line 326a. Energization of relay C closes a corresponding contact C in line 320. At this moment if the photocell A-1 senses the end of a board on the outfeed side of the defect saw but photocells A-2 and A-3 do not, the corresponding contact A-1 in line 320 also closes, causing the air cylinder on the first pop-out stop 180 to extend to set such stop and determine the specified long length to be cut.

On the other hand, if, at the time the PML relay is latched, both photocells A-1 and A-2 sense the downstream end of the piece, corresponding contacts A-1 and A-2 in line 321 close while the corresponding contact A-2 in line 320 opens, thereby extending the air cylinder on the second pop-out stop 181 to set that stop and determine a slightly longer specified length to be cut.

A third line 322 with normally open sensor contacts A-1, A-2 and A-3, all close when all three of the corresponding sensors detect the downstream end of a piece at the same time sensor PC-5 detects a marked defect. This event also opens the contacts A-3 in lines 320 and 321 so that only the third of the three pop-out stops 182 is set to determine the longest of the three specified clear lengths to be cut by the defect saw.

Sensors SA-1, SA-2 and SA-3 are retroreflective photocells which detect the end of a board as it approaches one of the stops and function to slow the drive rolls 162 to slow down the lumber before it reaches the set mechanical stop. These sensors have corresponding normally open contacts in line 324. When any one of such sensors senses a piece, it closes its corresponding contact in line 324 to energize time delay relay TD-2 which times out the deceleration period prior to stopping the lumber at the set mechanical stop. When relay TD-2 times out, it closes a contact TD-2 in line 323 thereby energizing a control relay KA. This relay has a contact KA in line 327 which closes when the relay is energized to stop drive rolls 162. Contacts PC-4 and SW-1 in parallel with contact TD-2 in line 323 also serves this function.

A single coil latching relay K-1 in line 325 is energized either when a relay contact KA is closed or a relay contact TD-6 is closed in the same line. Relay TD-6 is a time delay relay in line 344 controlling the time allowed for the defect saws to clear the piece before restarting drive rolls 162. Relay K-1 thus is controlled by the drive "start-stop" signals and includes a corresponding contact K-1 in line L to enable operation of the sorting gate circuitry.

Time delay relay TD-4 in line 338 can be energized either by closing limit switch contact SW-1 in line 338a or by closing relay contact K-1 through its corresponding latching relay K-1 in line 325. When time delay relay TD-4 times out, it closes contact TD-4 in line 328 to retract the air cylinder on the set one of the three pop-out stops.

A time delay relay TD-3 in line 329 controls the spacing between pieces of lumber fed into the defect station by the nip rolls 90. It controls the spacing by controlling the delay in reopening of infeed nip rolls 90. Relay TD-3 is energized when a contact PC-5 in line 329 closes. This contact is closed by the corresponding photocell PC-5. When relay TD-3 times out, it closes contact TD-3 in line 330 to open nip rolls 90.

The piece-present sensor PC-6 is also a retroreflective photocell which functions to reclose nip rolls 90 when a piece is present at the fence on the screw roll table by closing sensor contact PC-6 in line 331.

The remaining portion of the circuit controls the sorting from the defect station. As previously mentioned, it is necessary for the functioning of the sorting circuit for the normally open gate set-up control contact K-1 in line L to be closed by relay K-1 in line 325, which can only occur when drive rolls 61 are stopped.

The two outfeed sensors O-5 and O-10 are retroreflective photocells which measure a piece at 5 inches and 10 inches, respectively, downstream from the downstream defect saw 139. Sensor O-5 has normally open contacts O-5 in lines 332 and 333 and a normally closed contact O-5 in line 334. Outfeed sensor L-10 has a normally open contact in line 332 and normally closed contacts in lines 333 and 334. Thus if both sensors O-5 and O-10 sense the piece, indicating a piece longer than 10 inches on the outfeed side of the defect saws, contacts O-5 and O-10 in line 332 close to actuate the flip-flop gate 206 in FIG. 6 to a position for diverting the piece to the cut-to-length station. On the other hand, if only sensor O-5 senses the piece, line 332 remains open and line 334 is open, but line 333 closes, energizing control relay K-2. This relay closes relay contact K-2 in line 335a to close line 335 and position the flip-flop gate to divert the piece to the core block or junk sort. At the same time another relay contact K-2 in line 336 closes to open core block gate 209.

Similarly, if a piece on the outfeed side of the defect saws is less than 5 inches, neither lines 332 or 333 close, but line 334 remains closed, energizing relay K-3 which closes relay contacts K-3 in lines 335 and 337 to divert the short piece to junk, the line 337 controlling the junk sort gate.

The similar retroreflective photocell sensors I-5 and I-10 at the infeed side of the defect saws measure pieces at 5 inches and 10 inches, respectively, from upstream defect saw 138. If the piece upstream of the defect saws is shorter than 5 inches so that neither photocell is activated, the normally closed contacts in line 339 and 339a remain closed to open infeed junk gate 208. However, if the sensor I-5 is energized, the contact I-5 in line 339a opens and the contact I-5 in line 339 closes, opening infeed core block gate 209.

Now, however, assuming that the piece remaining upstream of the defect saws is so long that it energizes both sensors I-5 and I-10 indicating that its length is greater than 10 inches, neither the infeed core block gate nor the infeed junk gate opens, and contacts I-5 and I-10 in lines 346 and 346a open to prevent retraction of the short movable fence and release of the piece to the sorting area. In the meantime, time delay relay TD-6 times out and drive rollers 162 restart to feed the piece into the defect saws.

Time delay relay TD-4 in line 338 controls the time allowed for the defect saws to stroke before the movable fence retracts to drop the piece. Time delay relay TD-5 in line 341 controls the time allowed for the movable fences to operate. When relay TD-4 times out, it closes contact TD-4 in line 340 to retract the long movable fence 122 and drop the cut piece to the cut-to-length station. At the same time it closes contact TD-4 in line 341 to energize time delay relay TD-5. When relay TD-5 times out, it closes contacts TD-5 in lines 342 and 343 to extend the short and long movable fences 120, 122. The timing out of this relay also closes contact TD-5 in line 344 to energize relay TD-6. When relay TD-6 times out, it closes contact TD-6 in lines 345, 345a to restart drive rolls 162.

The retroreflective photocells are complete units including light source, pick-up, amplifier and output relay. The line scan photocells are complete with power supply, amplifier and relay. Both types of photocells are well known and readily commercially available.

PNEUMATIC-FLUIDIC CONTROL SYSTEM

Referring to the control logic diagram of FIG. 13, a pneumatic-fluidic control system is used for controlling the operation at the cut-to-length station and the sorting which takes place from the cut-to-length station.

The circuit includes an air supply line 360 supplying air to each of the 15 stop-sensors SS-1 through SS-15 positioned along stop-sensor bar 254 and also to piece-present sensor PP and random-length sensor RS on the bar. All these sensors are on one side of the cutting plane 234a of the cut-to-length saw. The air supply line also supplies air to two measuring sensors SS-5 and SS-10 on the opposite side of the cut-to-length saw.

From the construction of a typical stop-sensor SS as shown in FIG. 11, it will be seen that when the depressible stop lever of each stop-sensor is in its released position, there will be a relatively high back pressure in the various input lines 361 leading to the various pairs of input one-shot gates M-1 through M-4. This is the normal condition of the circuit when there is no board present at the cut-to-length station.

However, with no board present, random-length sensor RS, piece-present sensor PP and core block and junk-measuring sensors S-5 and S-10, all of which are normally open to atmosphere when unblocked, induce a relatively low back pressure in their input lines 362, 363, 364, 369, respectively, leading to their respective input gates M-6, M-8, M-9.

When a board arrives at the cut-to-length station normally blocking at least piece-present sensor PP and the random-length sensor RS, a relatively high back pressure is induced in their respective input lines 362, 363. Of course, when sensors S-5 and S-10 are blocked, there is a high back pressure output from these sensors also to their respective input gates.

However, when a board is pressed against the stop-sensors SS to depress their stop levers, a low pressure pulse is induced in their input lines 361. When one of the stop-sensors SS is released again, its input line 361 transmits a high pressure pulse.

The illustrated control circuit includes ten series of NOR gates M-1 through M-10 interconnected in such a manner with each other and connected to the various stop-sensors, random sensors and other sensors to operate the various elements at the cut-to-length station in the manner previously described under the heading "Operation at Cut-to-Length Station."

In addition to the NOR gates, the circuit includes three sorting gate manifolds 365, 370, 374. Manifold 365 controls the air supply through line 366 to a No. 1 sorting gate flip-flop circuit 367 which controls the opening and closing of the No. 1 sorting gate 274a through controlling the shifting of a No. 1 gate cylinder operating valve 368.

Manifold 370 controls the air supply to a second flip-flop circuit 367a through line 371 to control the shifting movement of the No. 2 sorting gate cylinder operating valve 372.

The third gate manifold 374 controls the supply of air through a line 375 to a third sorting gate flip-flop circuit 367b which controls the operation of the No. 3 sorting gate cylinder operating valve 376.

Lines 377 from each of the three sorting gate manifolds lead to a CTL flip-flop circuit 378 which controls signals to a drive reverse timing control one-shot circuit 380, including a variable timer D-4 and a pair of gates M-7. The CTL flip-flop circuit also controls the signal to a saw stroke time delay D-3, to saw stroke one-shot gates M-7 at 382, and to the CTL drive motor control valve 384. Signals from the saw stroke one-shot gates 382 are transmitted to a saw "single stroke" steerable flip-flop circuit 386 controlling the operation of the saw stroke control valve 388.

Because there are only three sorting gates which sort material to length but a total of 15 stop-sensors, the sensors are arranged in the circuit so that sensors SS-1, SS-5, SS-9 and SS-13, that is every fourth sensor, lead to manifold 365 so as to sort into the No. 1 sorting gate. Then sensors SS-2, SS-6 and so forth sort into the No. 2 sorting gate, and sensors SS-3, SS-7 and so forth sort into the No. 3 sorting gate. Sensors SS-4, SS-8 and SS-12 then can be arranged to either sort into the random sorting gate, not shown in the circuit, or connected so as not to actuate any of the gates whereby they are carried off on the transfer belts 284. In any event, the input gates for the sensors SS-4, SS-8, SS-12 are connected so as to transmit a signal into the CTL flip-flop circuit 378 in a manner, for example, shown with respect to the stop-sensor SS-8, which is typical of the way in which the input gates from sensors SS-4 and SS-12 would also be connected.

When random-length sensor RS is covered but downstream sensors SS-12, SS-13, etc., are not depressed, a high pressure air pulse is transitted from random-length sensor RS through input line 362 to a series of three gates M-6. These gates transmit a signal to a random-length flip-flop circuit 390 including a pair of gates M-8 which, in conjunction with downstream pairs of gates M-8 and M-7, maintain the CTL drive motor valve 384 in its neutral position so that the CTL drive does not operate. At the same time a signal shafts control valve 392 to operate the CTL drop gate and drop the random piece to its sorting area.

The piece-present sensor PP, when blocked, transmits a high pressure signal through line 363 to piece-present flip-flop circuit 394 including a pair of gates M-8, which controls the operation of a CTL fence control valve 396 and a fence-extend time delay D-1. At the same time a line 397 leading from sensor SS-15, under high pressure when sensor SS-15 is not depressed, leads to a series of three short length random control gates 398. These gates produce a signal which shifts the CTL drop gate valve 392 in a direction for opening the drop gate when only the piece-present sensor is blocked and none of the stop-sensors are depressed. These control gates also control the operation of a piece drop time delay D-2.

Further down the diagram of FIG. 13, measuring sensors S-5 and S-10, when blocked, transmit a high pressure pulse through a series of input gates M-9 to a junk gate flip-flop circuit 400 in the case of sensor S-5 and to a core block flip-flop circuit 402 in the case of sensor S-10. Flip-flop circuit 400 controls the operation of a CTL junk gate cylinder operating valve 404. Flip-flop circuit 402 controls the operation of a valve 406 for controlling the operation of the core block gate cylinder.

In typical operation of the logic circuit to cut a board to length, assume that a long, clear, random-length board drops to the cut-to-length station and is long enough to cover all of the 15 stop-sensors from SS-1 through SS-15. First the board blocks piece-present sensor PP, sending a high pressure signal to the flip-flop gates 394 and resulting in a high pressure signal to the "extend" side of the CTL fence-operating valve to shift the valve, whereby fence 224 and the drive-nip rolls press the board against the CTL stop bar 254, depressing all of the stop-sensors SS-1 through SS-15. At this time the stop-sensor input gates place the manifolds 365, 370, 374 under low pressure, closing the three sorting gates. The low pressure also causes CTL flip-flop circuit 378 to transmit a low pressure signal to the input side of the gate M-7 leading to the CTL drive motor control valve 384 whereby such gate transmits a high pressure output to the "forward" side of valve 384, causing the CTL drive roll to operate in a direction to feed the board endwise toward the saw cutting plane 234a. This endwise movement continues until stop SS-1 is released.

When stop-sensor SS-1 releases, its input gates M-1 send a high pressure signal into manifold 365 causing the No. 1 sorting gate valve 368 to shift to open the No. 1 sorting gate. At the same time, a high pressure signal from manifold 365 causes a high pressure input into the CTL flip-flop circuit 378, resulting in a high pressure input signal at the drive reverse timing one-shot 380 to shift the CTL drive motor valve 384 to its reverse position, reversing the direction of the CTL driven roll, and at the same time actuating the drive reverse timer D-4 and the saw stroke time delay D-3. Thus the board is driven back against the released stop lever of stop-sensor SS-1 and the CTL drive motor stops when timer D-4 times out. Thereafter time delay D-3 also times out, whereby the saw stroke one-shot 382 transmits a signal to saw stroke steerable flip-flop 386 which actuates the saw stroke operating valve 388 to stroke the saw. Thus the board is cut to specified length as determined by the distance of a stop-sensor SS-1 from the cutting plane 234a.

After the CTL saw strokes, piece drop time delay D-2 times out, permitting the CTL drop gate valve 392 to shift to open the drop gate, dropping the cut-to-length piece through the open No. 1 sorting gate. When the piece drops from the cut-to-length station, all of the stops are cleared and the piece-present sensor is opened causing the CTL fence to retract and the CTL drop gate to reclose to await arrival of the next piece.

With the foregoing description of the operation of the circuit, those skilled in the art should be able to trace the operation of the circuit for other lengths of boards, including short boards which cover only the piece-present sensor and longer boards extending only to random sensor RS. Under both mentioned conditions, the CTL drop gate opens without the drive motor operating and without the saw stroking.

Having illustrated and described a prototype of my invention and what is now a preferred embodiment thereof, it should be apparent to those skilled in the art that the same permits of modification in arrangement and detail. It will be apparent, for example, that various types of control circuits may be employed other than the typical electrical and fluidic circuits illustrated. It will also be obvious that various other sorting and transfer arrangements could be used. It may also be desirable in certain instances to increase the speed of production by providing two cut-to-length stations to which pieces are fed alternately from the defect-cutting station. In any event, I claim as my invention all such modifications coming within the true spirit and scope of the following claims.

Claims

I claim:

1. An apparatus for cutting lumber to specified lengths comprising:

length-cutting means defining a cutting plane,

stop bar means extending normal to said cutting plane and including a series of programmable depressible stop and length-sensing means spaced at predetermined distances from and on one side of said cutting plane corresponding to specified lengths of lumber to be cut,

means for delivering a random length of lumber to a position extending along said stop bar means with one end of said piece adjacent said cutting plane.

drive means for pressing said piece toward said stop bar means to depress one or more of said stop and sensing means and for driving said piece endwise in opposite directions along said stop bar means,

and control means operable in response to the presence of said piece along said stop bar means first to operate said drive means in one direction to drive said random length toward said cutting plane until a depressed one of said stop and sensing means is released and then in response to such release to reverse said drive means to drive the opposite end of said random length against said released stop means and then to actuate said cutting means to cut said random-length piece to the longest specified length as sensed by said stop and sensing means.

2. An apparatus according to claim 1 including drop gate means providing in its closed position a lumber-supporting surface extending normal to said cutting plane along said stop bar means, said control means being operable to open said gate means after the random length is cut to a specified length to discharge the resulting pieces from said apparatus.

3. Apparatus according to claim 2 including a sorting area below said drop gate means including a series of sorting gates for diverting lumber according to length to a series of sorting stations, said series of sorting gates being operable by specified-length sensings from said stop and sensing means.

4. Apparatus according to claim 1 including short length-sensing means on the opposite side of said cutting plane from said stop and sensing means, and means operable following the cutting operation in response to sensings from said short length-sensing means for diverting pices on said opposite side of greater than a predetermined minimum length to a first collection point and for diverting pieces on said opposite side of less than said predetermined length to a second collection point.

5. Apparatus according to claim 3 wherein said control means includes sensing means for sensing the presence of a piece of lumber adjacent said stop bar means positioned on said one side of said cutting plane and toward said cutting plane from the closest one of said stop and sensing means to said cutting plane, said control means being operable in response to a sensing from said piece-present sensor and the abscence of sensing from said stop and sensing means indicated the presence of a random-length piece shorter than the shortest specified length, to open said drop gate means and predetermined sorting gate means to divert said piece to a random-length sorting station without operating said cutting means.

6. Apparatus according to claim 1 wherein said control means comprises a pneumatic-fluidic logic circuit and said stop and sensing means includes pneumatic sensing means operable to input pressure signals into said logic circuit.

7. Apparatus according to claim 1 wherein said stop and sensing means are adjustable at small increments along said stop bar means.