US3748578A

US3748578A - Wood veneer moisture detection equipment located on a production line

Info

Publication number: US3748578A
Application number: US00188931A
Authority: US
Inventors: D Ward
Original assignee: D Ward
Current assignee: Coe Manufacturing Co
Priority date: 1971-10-13
Filing date: 1971-10-13
Publication date: 1973-07-24
Anticipated expiration: 1990-07-24

Abstract

Improvements in on-line wood veneer moisture detection equipment involve closer and protective positioning of wire brush electrical sensors and very efficient utilization of fewer conveyor components. These improvements insure only one transverse moisture sensing zone will be created, initiating in turn only one signal from each respective portion of a wood veneer having a designated excessive moisture content. The signal is used to actuate an ink marker, and the excessive moisture is located and eliminated to subsequently avoid any formation of blows and/or blisters during subsequent hot press operations. Also the signal is used for directly and indirectly controling the speed of the dryer in a closed loop system.

Description

United States Patent Ward [ 1 July 24, 1973 Primary Examiner-Stanley T. Krawczewicz Attorney-Roy E. Mattern, Jr.

[76] Inventor: Donald D. Ward, P. 0. Box l(.,

Sumner, Wash. 98390 [571 ABSTRACT [221 FM Oct-13,1971 IE3KZlfi B2122I5.32321flifalil iiilfiifio353531 [21] Appl. No.:-188,931 ing of wire brush electrical sensors and very efficient utilization of fewer conveyor components. These improvements insure only one transverse moisture sensg 324/65 118/ ing zone will be created, initiating in turn only one signal from each respective portion of a wood veneer [58] Field of Search 324/65 R, 65 P, 61 R, d t d t t t Th l 118 19! I 5 9'1 ng a esigna e excessrve mors ure con en e signa is used to actuate an ink marker, and the excessive moisture is located and eliminated to subsequently [56] References cued avoid any formation of blows and/or blisters during UNITED STATES PATENTS subsequent hot press operations. Also the signal is used 3,042,861 7/1962 Brys 324/65 R X for directly and indirectly controling the speed of the 3,391,337 7/1968 Preikschat......... 324/61 R dryer in a closed loop system 3,523,243 8/1970 Wagner 324/61 R 3,646,437 2/1972 Nutter 324/65 R 27 C 11 awing F gu es OK N0 MOISTURE ACTION 96 SENSING ELECTRQNICS REJECT MARKER NOZZLE 58 CURTAIN 3 ,9 HOLD DOWN CKU 64 44 ROLLER BRUS N VLEERZ :j FLOW CONVEYER END ROLLER 46 M QTA N 44 MOISTURE SENSING AREA P Ju 4 AIENIED l2 I975 3.748.578

' sum 2 or 5 PIC-3.3

H64 I PRIOR ART PAIENIEHJULZMQH SHEET 5 [1F 5 FIG. IO OK NO MoIsTURE AcTIoN 9e- SENSING ELEcTRoNIcs REJECT MARKER p90 NozzLE 58 cURTAIN 36 98 44 RO L LE BRU w T VENEER PAJNAH FLOW gg 6O MARI lINe 28 E D LLE 46 POINT 44 I-- MOISTURE SENSING AREA FIGII OK NO MoIsTURE AcTIoN ExIT GUIDE GUARD ROLLERS VENEER RoLLER 'gg'fifl O PANEL @FLOW coNvEYER Q) [if END ROLLER ZONE I zoNE 2 M x R I IIue MIRSTURE SHIEING AREA PRIOR ART WOOD VENEER MOISTURE DETECTION EQUIPMENT LOCATED ON A PRODUCTION LINE BACKGROUND OF INVENTION Wood veneer moisture detection equipment of similar purpose using wire brush electrical sensorshas been used before and typical of such equipment is a system marketed by Mann-Russell Electronics Inc.of Takoma, Washington and illustrated in a Mann-Russell Engineering Manual entitled Cross Tipple Moisture Detector. However, such prior equipment has included a large number of conveyor components to control the fast moving wood veneers to keep them properly orientated with respect to the wire brush sensors. Such additional conveyor components, centered on a set of pinch rollers, and necessitated a longer overall conveyor. Moreover, the components thereof were involved in establishing two transverse moisture sensing zones initiating two signals from each respective portion of a wood veneer having a designated excessive moisture content. Therefore, there remained an important need for having wood veneer detection equipment creating only one transverse moisture sensing zone improving the accuracy of the moisture detection.

SUMMARY OF INVENTION Wood veneer moisture detection equipment is now installed in a production line, beyond a dryer, using a minimum in line space by incorporating fewer conveyor components. During operations, only one transverse moisture sensing zone is created, thereby improving the accuracy of the signals, and also the markings indicating where there is excessive moisture.

The changes in the conveyor were undetaken in conjunction with the astute close in placement of the wire brush electrical sensors. They are now uniquely protected from damage and from touching conveyor components by using their own guards, thereby avoiding false signals.

As a consequence, the sensing signals are more accurate. They initiate prompt ink marking of designated excessive moisture locations of critical magnitude. Such markings and their observation followed by corrective action thereby avoids the unwanted inclusion of veneers in plywood, which during subsequent hot press operations would otherwise by the source of probable blows and/or blisters ruining the quality of the plywood product. Moreover, the increase accuracy of the sensing signals and markings has resulted, oftentimes, in overall increases in the speeds of the production line equipment.

DRAWINGS or PREFERRED EMBODIMENT FIG. 1 is a perspective view of the wood veneer moisture detection equipment located on a production line in conjunction with a cross tipple conveyor receiving veneers from a dryer;

FIG. 2 is a plan view of a production line, showing a dryer, cross tipple conveyor, wood veneer moisture detection equipment located at the end of a cross tipple conveyor, a dry chain conveyor, wood veneer moisture detection equipment shown in dotted lines to indicate an alternative location across a dry chain conveyor, and pieces of veneer traveling on the respective conveyors in the directions indicated by the arrows;

FIG. 3 is a side view, with some portions shown in section and others shown partially, indicating the positioning of this improved wood veneer moisture detectionequipment located at the end of a cross tipple conveyor, and also showing the close and protective positioning of the wire brush electrical sensors operating adjacent to the pinch rollers of the crosstipple conveyor;

FIG. 4 is a side view, with some portions shown in section and others shown partially, indicating the positioning of the prior Mann-Russell wood veneer moisture detection equipment located at the end of a cross tipple conveyor, to illustrate the protective positioning of the wire brush electrical sensors located midway between two sets of pinch rollers well spaced respectively ahead and behind these sensors with respect to this added length of the conveyor system;

FIG. 5, is a partial perspective of the arrangement of the wire brush electrical sensors and their mounting sub assembly indicating how two rows of brushes are used in contacting the entire transverse area of the passing veneers;

FIG. 6, is a side view of some mounting components holding one wire brush electrical sensor in the cross tipple moisture detector, the arcs indicating respectively the otherwise free swinging radius of the bristles of stainless steel and their restrained or guarded swinging radius;

FIG. 7, is a side view of some mounting components holding one wire brush electrical sensor in the dry chain moisture detector, the arcs indicating respectively the otherwisefree swinging radius of the bristles of stainless steel and their restrained or guarded swinging radius;

FIG. 8, is a perspective view of the wood veneer moisture detection equipment located on a production line in conjunction with a dry chain conveyor, wherein this detection equipment includes a set of transversely spaced and powered plastic wheels to raise the oncoming veneers above the continuing driven belts of the dry chain conveyor, while the moving veneers are being contacted by the'stainless steel wire brush electrical sensors, to thereby eliminate any possibility of false signals caused by moisture carried by the dry chain conveyor components;

FIG. 9, is a partial side elevation, with some components shown in section or in part, of the dry chain moisture detector, with arcs indicating the swinging scope of the guarded stainless steel bristles of the electrical sensors, and with arrows indicating both the direction of the conveyor and the rotational direction of the veneer lifting plastic wheels;

FIG. 10, is a schematic-elevational view of the relative positionsof various selected components'of the improved cross tipple moisture detector, to indicate the use of only one set of pinch rollers serving as hold down and guide rollers with the resulting establishment of only one moisture sensing zone or area located at and before the stainless steel wire sensing brushes, which, when guarded, are moved near the one set of rollers, thereby also eliminating any possible need for a time delay relay with respect to when the marker nozzle be comes effective; and

FIG. 11, is a schematic elevational view of the relative positions of various selected components of the prior Mann-Russell cross tipple moisture detector, indicating the former use of -two sets of pinch rollers serving as hold down and guide rollers, with the resulting establishment of two moisture sensing zones or areas located both before and after the stainless steel wire crease in conveyor length often requires the incorporation of a time delay relay with respect to when the marker nozzle is actuated.

DESCRIPTION OF PREFERRED EMBODIMENTS Detection of Moisture in Veneer Sheets In the lumber and plywood industry there is always concern for knowing what the moisture content is in wood being processed. This is especially true in reference to the manufacture of plywood. An excessively wet veneer incorporated into plywood products very often may contain sufficient concentrations of moisture so blows and/or blisters occur in the plywood during hot press operations.

This moisture detection equipment includes improvements making the monitoring and marking of excessive moisture more accurate. Also these improvements have resulted in reducing the initial capital investment and the follow on operating and maintenance costs. Moreover, the increased accuracy in creating signals and marking the veneers based on excessive moisture content has resulted in a better analysis of the permissible moisture content in the veneer sheets. As an important consequence, the drying time has often been reduced and the entire production line has been operated at a faster rate. The more accurately marked veneers are effectively removed, when necessary, before being unwantedly included in a plywood product. As this has been accomplished, any necessity for the more complete removal of moisture from veneers has been avoided. There is no possibility that the' evils of over drying are to be encountered.

There is always a need for selectable speeds of production operations, as they may have to be varied from time to time depending primarily on the initial moisture contained in veneers, to keep the veneer dryers, conveyors, and plywood hot presses always running at optimum speeds. Therefore this moisture detection equipment accurately only creates signals and causes marking on veneers when in fact there are concentrations of moisture which will likely cause blows and/or blisters in plywood products during hot press operations.

Improvements of Veneer Moisture Detection Equipment As illustrated in FIGS. 4 and 11, the previous Mann- Russell veneer moisture detection equipment had essentially self contained conveyor components to restrictably guide. veneers past the moisture sensing equipment. The components'of these'self contained conveyor assemblies established two-zonesof transverse moisture sensing areas, one ahead of the sensors and another beyond the sensor. These two zones created dual signals each of which was concerned with the identical moisture location and its respective concentration. Yet only one marking of the moisture location is ever wanted. The double signals caused problems of control and selectivity of'the overall response of the moisture detection equipment. Often the signals and markings were most excessive than the actual critical moisture conditions might have warranted.

Therefore, as illustrated particularly in FIGS. 1, 3, and 10, this moisture detection equipment includes improvements which eliminate one of the dual zones and this notably increases the accuracy. As a consequence,

the observations of the excessive moisture signals and markings, present a more meaningful understanding of the actual moisture content of the veneers and oftentimes the production rate of the plywood may be increased.

The elimination of the one unnecessary transverse moisture sensing zone is principally accomplished, as illustrated particularly in FIGS. 1,3, 5, 6 and 7 by guarding the sensors and moving them, in a subassembly, closer to regular conveyor components. In so doing, the number of conveyor components self contained on the veneer moisture detection equipment is substantially reduced. Such reduction makes it possible to manufacture, install, operate, and maintain this im proved veneer moisture detection equipment at a much lower overall cost. Also this improved moisture detection equipment may be installed in existing production lines where space is very limited and where the prior moisture detection equipment could not be readily installed without substantial changes and/or relocations of other plywood production line equipment.

Alternate Locations for Installing Wood Veneer Moisture Detection Equipment As indicated in FIG. 2, this improved wood veneer moisture detection equipment, in selected

respective embodiments

20, 22, may be installed in different locations. For example, embodiment 20, referred to as the cross tipple detector, is installed at the exit 24 of the cross tipple conveyor 26 which is bringing wood veneers 28 from a, dryer 30. Or, embodiment 22, shown in dotted lines, referred to as the dry chain detector may be installed along the dry chain conveyor 32.

Wood Veneer Moisture Detection Equipment Located at the Delivery End of the Cross Tipple Conveyor The wood veneer moisture detection equipment 20, shown in FIGS. 1, 2 and 3, is arranged for placement at the exit end 24, of the cross tipple conveyor 26, which is carrying the veneers 28 endwise to this embodiment referred to as the cross tipple detector 20. The cross tipple conveyor 26 is modified by installing an upper hold down roller 36, using support arms 38 which are pivotally mounted to brackets 40 on frame 42 of conveyor 26. The height adjustment of roller 36 is undertaken using the threaded spacing assembly 34. Upon its proper adjustment, upper roller 36 combines withmoving conveyor belts 44, traveling about the lower head shaft 46, to perform the holding and guiding functions of a pair of pinch rollers.

A frame 50 of this cross tipple detector 20 has side leg members 52 which support various cross members such as a cross bar 54. Depending from this bar 54 are many positioning subassemblies 56 for holding stainless steel wire brush pick ups 58. They, in turn, are positioned to collectively and fully contact wood veneers 28 leaving the cross'tipple conveyor 26. This frame 50 is positioned closely about the termination 24 of the cross tipple conveyor 26, so the wood veneers 28, passing between the upper hold down roller 36 and the conveyor belts 44, backed up by head shaft 46, will remain sufficiently under guiding control during the moisture detection operations, without creating any necessity for having additional pinch rollers installed in conjunction with the cross tipple moisture detector 20. By having this arrangement, no second moisture sensing zone is established and there is only a very minor addition made to the overall length of the plywood production line.

As the wood veneers pass by the contact bristle electrodes 64, the effective resistivity of the bristles varies as they contact wet spots on the wood. As a result, the effective impedance between contact bristles 64 and the pick up electrodes formed by

rolls

36 and 46 varies. This variable impedance forms one leg of a conventional bridge circuit which is part of the overall electrical control circuit housed within housing 96. The bridge becomes unbalanced as a function of moisture content of the wood and generates a voltage signal which is compared to a reference voltage signal, the value of which is a function of the moisture content desired. When the unbalanced signal exceeds the reference signal in value, a control signal is produced to activate a marking unit 90 to mark the zone of wood being sensed. The detailed control circuitry may be essentially the same as that employed in the prior Mann- Russell system and, for purposes of clarity, it is not illustrated in detail in this application.

Guarded Stainless Steel Wire Brush Pick Ups and Their Positioning Subassemblies When the cross tipple moisture detectoris installed so closely to the cross tipple conveyor 26, and when the positioning subassemblies 56 with the electrodes, or pick ups, such as stainless steel wire brushes 58, are placed so closely to the Operating conveyor parts, then non conducting plastic guards 60 are included in these positioning subassemblies 56, as shown in FIGS. 1, 3, 5, 6 and 7. They may have a lower offset rest bar 62, as shown in FIG. 6, or they may extend directly without change, as shown in FIG. 7.

As particularly noted in these FIGS. 6 and 7, the guards 60 restrictively change the radius and scope of the flexing stainless steel wires or bristles 64 so they will not contact the moving conveyor components. Also the non conducting'guards 60 serve as direct protection for the flexing stainless steel bristles or wires with respect to any possible damage to be otherwise caused by a fast moving segment of a veneer 28 or the end of the veneer 28 as it clears the cross tipple conveyor 26.

As further illustrated in FIG. 5, another non conducting spacing and positioning support member 68 is used inmounting the sub assemblies 56 below the cross bar 54. These non conducting guards 60 and spacers 68 generally made of plastic are joined together by a metal diagonal mounting bracket 70, using fasteners 72. Itv in turn supports the wire brush pickups 58 as they are secured by partially encompassing holders 74 held in place by fasteners 76. The electrical energy is conductedthrough respective wires 78 secured by fasteners 80 to respective metal diagonal mounting brackets 70 and arrangedfto be connected above to circuit components contained in the cross or.transverse housing 84.

The adjacent subassemblies 56 holding the wire brush pick ups 58 are staggered in the direction of conveyor motion, as the spacers 68 are alternately secured to the front or rear of the cross bar 54 using fasteners 86. As indicated in FIG. 3, those positioning subassemblies 56 for the wire brushes 58, which are mounted at the'rear of cross bar 54, do not have a non conducting guard 60 because the protection offered by the other guards 6G is relied upon. Also there is no need at this rearward position to restrict the free flexure of the wires or brushes 64 of these staggered wire brush pick -ups 58. I

Close In Placement of Veneer Marking Units Continuing with the overall objectives of operating with one moisture sensing transverse zone and closely arranged components to improve the accuracy of the moisture detector 20, while at the same time reducing overall costs, the veneer marking spray units are closely arranged nearby their respective wire brush pick ups 58. They are mounted at spaced intervals along a cross ink supply pipe 92 and a compressed air supply line 93 which are supported in turn by the cross housing 84. As a result of such close follow on mounting of these marking spray units 90, no time delay devices are incorporated into the overall electrical control system which is principally arranged within cabinet 96. However an ink or dye spray curtain or shield 98 is used to deflect any sprayed dye or ink which might otherwise reach the wires or bristles 64 of the wire brush pick up 58. It is secured below the cross housing 84, as shown in FIG. 3, where also is shown the compressed air fluid line 87, the dye fluid line 88, and the electrical signal wire 89, which all serve the marking spray units 90. The replaceable source of the ink or dye fluid is illustrated in FIGS. 1 and'8, a container 130 being used from which ink or dye is drawn up through line 132.

Wood Veneer Moisture Detection Equipment Located Along the Dry Chain Conveyor As indicated in FIG. 2, by dotted lines, wood veneer moisture detection equipment 22 may optionally be located along the dry chain conveyor 32 which is carrying the veneers 28 crosswise to this embodiment referred to as the dry chain detector 22. As illustrated in FIG. 8, a frame 102 of this dry chain detector 22 is built up and over the dry chain conveyor 32 so the dry chain moving belts 106 continue right on below transverse member. 104 of this frame 102.

However, as observed in FIGS. 8 and 9, the moving veneers 28 are raised up and over powered plastic wheels 110 which are positioned in part above the dry chain moving belts 106. This conveyor lift off occurring at the same time the one zone moisture sensing is occurring, insures the moisture detection readings will not include any recognition for moisture being carried by the components of the dry chainconveyor 32. These plastic wheels 110 are secured to a shaft 1l2mounted in turn to the frame 102 of the dry chain detector 22. Also secured to the shaft 112 is a driven pulley wheel 114 being driven by a moving belt 116. This belt 116 in turn-is powered by the same power source, not shown, driving the dry chain conveyor 32.

Guarded Stainless Steel Wire Brush Pick Ups and Their Positioning Sub Assemblies- As shown in FIGS. 8 and 9, one transverse row of wire brush pick ups 58 are selected for use in this dry chain detector 22. As indicated in FIGS. 7 and 9, a plasticnon conducting guard 60 is used to protect the wires or bristles 64 and to control their flexure so unwanted conveyorcontacts will not occur. Also for further protection and for inspection and repairs these positioning subassemblies 118 may pivot upwardly around hinge 120. In addition a combination guide, deflector, and guard 112 extends below the transverse member 104 of the frame 22.

Only One Transverse Moisture SensingZone and Its Protected and Electrically Shielded Components As illustrated in FIG. 9,- the stainless steel wire brushes serve as effective electrodes and they are well protected by the non conducting guards 60, and the deflectors 122. Also the pick up electrodes 124 are partially enclosed within an electrical shield 126. These pick up electrodes 124 are used in conjunction with this dry chain detector 22, for the lift off over the plastic wheels 110 isolates the electrical sensors from any conveyor components, which might serve the function of the pick up electrodes, as the upper hold down roller 36 subassembly functions in the cross tipple detector 20. Wherever mounted, the shielded electrodes 124 together with the wire brush pick ups 58 determine the electrical sensing zone which is also restricted in size as much as possible to keep the overall moisture sensing equipment as compact as possible. The effective resistivity of bristle electrodes 64 varies as the electrodes contact wet spots on the wood and consequently the effective impedance between contact electrodes 64 and pick up electrode 124 changes as an indication of the moisture condition of the zone being sensed on the wood.

Preferably the veneer marking spray units 90 are mounted as close as possible to the moisture sensing zone, as the operational time sequences of the electronic equipment 96 will allow. This avoids any need for time delay components with respect to the operations of the dye or ink sprayers 90.

Electrical Circuit Design In most of the electrical circuits, not illustrated, there are included capacitive'bridge circuits, analog operational amplifiers, S.C.R. switching units, adjustable master time delay controls to allow small concentrations of moisture to pass through without being marked, time integrating filters to block signals caused by other than excessive moisture, and monitoring controls to cause possible speed changes throughout the overall plywood production line. For example, the signal triggering the marking devices are used also for directly or indirectly controlling the speed of the dryer in a closed loop system.

As mentioned previously the actual electrical circuitry employed in the invention may be of any suitable type, e.g., the circuitry used in the prior Mann-Russell system.

SUMMARY OF ADVANTAGES As particularly illustrated in the diagrams of FIGS. 10 and 11, these improved wood veneer moisture detectors and 22, by establishing only one possible moisture sensing area, provide the means for making much more accurate determinations of excessive moisture content in wood veneers 28. Also the fewer conveyor components, while most importantly eliminating any possible creation of an unwanted moisture sensing area, moreover do account for substantial overall cost savings. The guarded wire brush pick ups 58 mounted in closer to regular conveyor components are essential in eliminating additional conveyor components and reducing the overall conveyor lengths. Consequently, compact cross tipple moisture detectors 20 and dry chain moisture detectors 22 may be mounted and effectively used in all locations where they are needed. They produce more accurate markings often leading to the speed up of entire production lines while still maintaining the quality of the plywood products by avoiding blows and blisters that might otherwise occur during hot press operations.

I claim:

5 a. a support for spanning the production line;

b. multiple contact electrodes secured to the support to make substantially a full transverse contact with passing wood veneers moved by production line conveyors; and

10 c. pick up electrode means spaced from the multiple contact electrodes to complete a single transverse zone in which moisture is being detected.

2. Wood veneer moisture detection equipment, as claimed in claim 1, wherein, guards are positioned near the multiple contact electrodes to prevent portions of wood veneers and veneers from damaging them and to prevent portions of these contact electrodes from contacting the production conveyor.

3. Wood veneer moisture detection equipment, as claimed in claim 1, having an electrical sensor system connected to the multiple contact electrodes and pick up electrode means.

4. Wood veneer moisture detection equipment, as 5 claimed in claim 1, wherein the pick up electrode means is part of an upper hold down roller means locatedto serve with the production conveyor the function of pinch rollers to guide wood veneers by the multiple contact electrodes.

Kll

5. Wood veneer moisture detection equipment, as

claimed in claim 1, wherein the pick up electrodes means are electrically shielded in part and spaced above the passing wood veneers follow-ing their contact with the multiple contact electrodes.

6. Wood veneer moisture detection equipment, as

claimed in claim 5, having spaced transverse lifting means secured to the support to lift the wood veneers above the production line conveyor to be contacted by the multiple contact electrodes in a moisture detection zone determined by these electrodes and the pick up electrodes spaced above.

7. Wood veneer moisture detection equipment, as claimed in claim 6, wherein the spaced transverse lifting means are spaced non conductive wheels mounted on a shaft in turn positioned on the support.

claimed in claim 1 wherein the multiple contact electrodes are wire brushes.

10. Wood veneer moisture detection equipment, as claimed in claim 1, wherein the multiple contact electrodes are stainless steel wire brushes.

1]. Wood veneer moisture detection equipment, as claimed in claim 9, wherein guards are positioned near the multiple wire brush contact electrodes to prevent portions of wood veneers and veneers from damaging them and to prevent portions of these wire brush contact electrodes from contacting the production conveyor.

12. Wood veneer moisture detection equipment, as claimed in claim 11, wherein the guards are non conductive.

13. Wood veneer moisture detection equipment, as claimed in claim 12, wherein the non conductive guards are made of plastic.

14. Wood veneer moisture detection equipment, as claimed in claim 11, wherein the guards are positioned to partially limit the otherwise free deflection arc of the wire brushes.

15. Wood veneer moisture detection equipment, as claimed in claim 11, wherein the guards are positioned on one side of the wire brushes to partially limit the otherwise free deflection arc of the wire brushes to pre vent contact with the production line conveyor.

16. Wood veneer moisture detection equipment, as claimed in claim 3, wherein the electrical sensor system generates signals adapted to be used to control production line equipment such as a veneer dryer.

17. Wood veneer moisture detection equipment located on a plywood production line beyond a dryer to effectively mark wood veneers in places where excessive moisture is still present to avoid the possible occurrence of blows and blisters during subsequent hot press operations, having only one transverse moisture sensing zone to thereby improve the accuracy of the signalling and related marking components, comprising:

a. a support spanning the production line;

b. multiple stainless steel wire bristle contact sensing electrodes secured to the support to make side by side contacts forming together a substantially full overall transverse contact with passing wood veneers moved by the conveying forces of production line conveyors;

c. pick up electrode means spaced from these multiple contact sensing electrodes to complete a single transverse zone in which moisture is being detected; and

d. guiding means to control the moving veneers during sliding contact with multiple stainless steel wire bristled sensing electrodes so arranged to insure only a single transverse zone of moisture sensing is established.

18. Wood veneer moisture detection equipment, as

claimed in claim 17, wherein the guiding means is an upper hold down roller means serving in conjunction with a production line conveyor to perform pinch roller functions in guiding the wood veneers during their contact with the steel wire bristled sensing electrodes.

19. Wood veneer moisture detection equipment, as claimed in claim 18, wherein the pick up electrode means is combined with the upper hold down roller means in establishing only a single transverse zone of moisture sensing. v

20. Wood veneer moisture detection equipment, as claimed-in claim 18, wherein guards are installed with the stainless steel wire bristle contact sensing electrodes to partially-limit the otherwise free deflection arc of the bristles to prevent them from entering the operational area, where the upper hold down roller means is performing a pinch roller function, as they in turn are mounted in close to utilize effectively the wood veneer guiding control occurring as a result of this pinch roller function, thereby avoiding any necessity for having additional pinch roller means, which might cause the unwanted creation of another transverse zone of moisture sensing.

21. Wood veneer moisture detection equipment, as claimed in claim 17, wherein the guiding means is a group of spaced non conducting wheels capable of lifting the wood veneers clear of any production conveyor components during their moving contacts with the stainles steel wire bristle contact sensing electrodes.

22. Wood veneer moisture detection equipment, as claimed in claim 21, wherein guards are installed with the stainless steel wire bristle contact sensing electrodes to protect the wire bristles from injury to be otherwise possibly caused by wood veneers and pieces thereof.

23. Wood veneer moisture detection equipment, as claimed in claim 22, wherein the spaced non conducting wheels are made of plastic.

24. Moisture sensing, apparatus adapted to sense the moisture condition of a material such as wood or the like travelling along a production path comprising support means located adjacent the path of travel of said material, moisture sensing means mounted on said support means and including flexible sensing electrode means adapted to contact said material as it passes thereby, and guard means mounted adjacent said flexible electrode means to protect said electrode means from damage and to limit the rearward deflection of said electrode means.

25. Moisture sensing apparatus as defined in claim 24, said electrode means comprising a plurality of flexible conductors adapted to contact said material, and said guard means being mounted adjacent said conductors and limiting the arc through which said conductors may be deflected in a rearward direction along said path of travel.

26. Moisture sensing apparatus as defined in claim 25 comprising a plurality of said flexible sensing electrode means extending transversely across the path of' travel of said material, and means for mounting said electrode means on said support means so that adjacent electrode means are isolated from each other.

27. Moisture sensing apparatus as defined in claim 25, said guard means being constructed of a nonconducting material.

Claims

1. Wood veneer moisture detection equipment adapted for use along a production line to sense the moisture condition of wood veneers moving therealong comprising: a. a support for spanning the production line; b. multiple contact electrodes secured to the support to make substantially a full transverse contact with passing wood veneers moved by production line conveyors; and c. pick up electrode means spaced from the multiple contact electrodes to complete a single transverse zone in which moisture is being detected.

4. Wood veneer moisture detection equipment, as claimed in claim 1, wherein the pick up electrode means is part of an upper hold down roller means located to serve with the production conveyor the function of pinch rollers to guide wood veneers by the multiple contact electrodes.

5. Wood veneer moisture detection equipment, as claimed in claim 1, wherein the pick up electrodes means are electrically shielded in part and spaced above the passing wood veneers follow-ing their contact with the multiple contact electrodes.

6. Wood veneer moisture detection equipment, as claimed in claim 5, having spaced transverse lifting means secured to the support to lift the wood veneers above the production line conveyor to be contacted by the multiple contact electrodes in a moisture detection zone determined by these electrodes and the pick up electrodes spaced above.

8. Wood veneer moisture detection equipment, as claimed in claim 7, wherein the non conductive wheels are made of plastic.

9. Wood veneer moisture detection equipment, as claimed in claim 1 wherein the multiple contact electrodes are wire brushes.

11. Wood veneer moisture detection equipment, as claimed in claim 9, wherein guards are positioned near the multiple wire brush contact electrodes to prevent portions of wood veneers and veneers from damaging them and to prevent portions of these wire brush contact electrodes from contacting the production conveyor.

15. Wood veneer moisture detection equipment, as claimed in claim 11, wherein the guards are positioned on one side of the wire brushes to partially limit the otherwise free deflection arc of the wire brushes to prevent contact with the production line conveyor.

17. Wood veneer moisture detection equipment located on a plywood production line beyond a dryer to effectively mark wood veneers in places where excessive moisture is still present to avoid the possible occurrence of blows and blisters during subsequent hot press operations, having only one transverse moisture sensing zone to thereby improve the accuracy of the signalling and related marking components, comprising: a. a support spanning the production line; b. multiple stainless steel wire bristle contact sensing electrodes secured to the support to make side by side contacts forming together a substantially full overall transverse contact with passing wood veneers moved by the conveying forces of production line conveyors; c. pick up electrode means spaced from these multiple contact sensing electrodes to complete a single transverse zone in which moisture is being detected; and d. guiding means to control the moving veneers during sliding contact with multiple stainless steel wire bristled sensing electrodes so arranged to insure only a single transverse zone of moisture sensing is established.

18. Wood veneer moisture detection equipment, as claimed in claim 17, wherein the guiding means is an upper hold down roller means serving in conjunction with a production line conveyor to perform pinch roller functions in guiding the wood veneers during their contact with the steel wire bristled sensing electrodes.

19. Wood veneer moisture detection equipment, as claimed in claim 18, wherein the pick up electrode means is combined with the upper hold down roller means in establishing only a single transverse zone of moisture sensing.

20. Wood veneer moisture detection equipment, as claimed in claim 18, wherein guards are installed with the stainless steel wire bristle contact sensing electrodes to partially limit the otherwise free deflection arc of the bristles to prevent them from entering the operational area, where the upper hold down roller means is performing a pinch roller function, as they in turn are mounted in close to utilize effectively the wood veneer guiding control occurring as a result of this pinch roller function, thereby avoiding any necessity for having additional pinch roller means, which might cause the unwanted creation of another transverse zone of moisture sensing.

24. Moisture sensing apparatus adapted to sense the moisture condition of a material such as wood or the like travelling along a production path comprising support means located adjacent the path of travel of said material, moisture sensing means mounted on said support means and including flexible sensing electrode means adapted to contact said material as it passes thereby, and guard means mounted adjacent said flexible electrode means tO protect said electrode means from damage and to limit the rearward deflection of said electrode means.

26. Moisture sensing apparatus as defined in claim 25, comprising a plurality of said flexible sensing electrode means extending transversely across the path of travel of said material, and means for mounting said electrode means on said support means so that adjacent electrode means are isolated from each other.

27. Moisture sensing apparatus as defined in claim 25, said guard means being constructed of a non-conducting material.