CA1270694A - Wood product manufacturing process and system - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A relatively simple press for producing oriented strand waferboard includes a first endless conveyor for receiving a mixture of wafers and resin to form a wafer or strand oriented mat, which is carried into a press including a second endless conveyor above and spaced from the first conveyor for defining a mat receiving gap, a pair of endless chain assemblies within the conveyor loops for applying heat and pressure to the mat, each assembly including contiguous, pivotally interconnected containers which are filled with a liquid so that the containers can be heated by catalytic heaters located within the conveyor loops on the sides of the chain assemblies opposite the mat receiving gap, and a plurality of rows of rollers in the endless chain assembly for applying uniform pressure to the mat. The sheet of waferboard produced by the press can be used as is, or by the use of suitable adhesives remain in a plastic condition for corrugation in forming rollers. Closed, triangular corrugations can be produced by feeding the already partially corrugated, still flexible board through an extruder where longitudinally extending, closed triangular corrugations are formed. The corrugations can be filled with a foam insulation before being discharged from the extruder, and one side of the corrugated panel coated with plaster to produce an inside finished, insulated wall panel.

Description

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This inventlon re]ates ~o a ~.rocess and apE~aral;u-.
for produci~g a reconstituted wood product, and to the product thus produced, and is a divlslon of Canada ~atent Application Serial No. 599177 filed May 17th 1989.
More specifically, the invention relates to the production of oriented strand or waferboard, roll formed corrugated waferboard or extruded corrugated waferboard.
Presses for the continuous production of fibreboard, chipboard or corrugated cardboard are described, for example in Canadian Patents Nos. 920,934, issued to H.J.
Knapp on ~ebruary 13, l973; 1,003,738, issued to A. DeMets on January 18, 1977 and 1,132,895, issued to S. Petersson et al on October 5, 1982, and United States Patents Nos.

2,720,231, issued to H.E. Hessler et al on October 11, 1955;
2,975,470, issued to H.J. Snelson et al on March 21, 1961;

3,795,470, issued to A. DeMets on March 5, 1974; 3,876,359, issued to A.K. Herr on April 8, 1975 and 3,833,284, issued to A. DeMets on May 13, 1975. In spite of the existence of such patents, a need still exists for a quick, efficient apparatus for producing compressed waferboard and the like.
An object of the present invention is to meet the above defined need by providing a relatively simple press for producing oriented strand board.
Another object of the invention is to provide an extruder for producing a waferboard with longitudinally 9~

extendincJ, cont:iglio~lx, trlangll]ar l()rr~lgdt:i~ s.
In accordance with one aspect, the inventior rela-tes to a press for use in the production of reconstituted wood panels of the type including a mixture of wood flakes and resin bound together by heat and pressure, said press comprising first, lower endless chain means for supporting and applying heat to a mat of said mixture during passage through the press; second, upper endless chain means for applying heat and pressure to said mat during passage thereof through the press, whereby the mat is compre~sed and formed into a unitary panel during passage through the press, each said endless chain means including a plurality of fluid-containing, closed container means pivotally interconnected in side by side rela-tionship; and heater means proximate said first and second endless chain means for heating the fluid in said container means.
In accordance with another aspectl the invention relates to an extruder for forming a reconstituted wood sheet with triangular corrugations from a flexible sheet of wood flakes and resin comprising elongated casing means;
inlet means in one end of said casing means for receiving a flexible sheet; outlet means in the other end of said casing means for discharging a finished corrugated sheet from the casing means; and passage means extending between the inlet means and outlet means, the cross section of said passage i;27(~

means chan~ing from said inlet means to sald outiet mearl., whereby the crc)ss sectional corlfiguration of the sheet is altered durirlg passage through said casing means to a final configuration of alternating, contiguous, triangular corrugations.
The invention will be described in detail with reference to the accompanying drawings, which illustrate preferred embodiments of -the invention, and wherein:
Figure 1 is a schematic flow diagram Gf a complete assembly line for producing oriented strand board;
Figure 2 is a schematic flow diagram of a portion of an alternative form of assembly line for producing medium density board;
Figure 3 is a perspective view of a press used in the assembly line of Fig. 1 on a larger scale;
Figure 4, which is located on the second sheet of drawings, is a cxoss-sectional view of a portion of an endless chain assembly used in the press of Fig. 3;
Figure 5 is a schematic plan view of a section of the endless chain assembly of Fig. 3 showing pressure roller locations;
Figure 6 is a schematic flow diagram of the portion of the assembly line of Fig. 1 following the press for producing oriented strand board;
Figure 7 is a schematic flow diagram of the 127(?~9~

portion of the assemllly l1ne ~)f l`ig. 1 f-,llow-ing thf' press for producincl a corrugated waferboard;
Figure 8 is a schematic flow diagrar,l of the portion of the assembly of Fig. 1 follow1ng the press for producing a plaster coated, corrugated waferboard;
Figure 9 is a schematic plan view of an extruder for use in the assembly line of Fig. 8 with the top removed;
Figure 1~ is a cross section taken generally along line X-X of Fig. 9;
Figure 11 is an end view of the extruder of Figs. 9 and 10;
Figures 12 to 16 are cross sections taken generally along lines XII-XII to XVI-X~I of Fig. 9; and Figure 17 is a partly sectioned, perspective view of one corner of a building constructed using the products of the present invention.
LOG HANDLING
With reference to Fig. 1, the process of the present invention starts at a log storage area 1. In the present case, the log storage area 1 includes a crane 2 mounted on a track 3 for manipulating tree length logs 4 stored in a large diameter circle. Alternatively, all logs delivered to the plant are in eight foot lengths, and are stored in stacks for manipulation by lift trucks (not shown). The crane 2 moves logs 4 from the storage area 1 to a log handling deck 6. Deck chains in the deck 6 transfer the logs onto a main chair~ collveyor 7, whi-h rno-~es Ihe J(Jg~
throuc3h a computer scanner ~ which deterrnines any cut-j to t~e made by a saw 10. After passlng the saw 10, the logs 4 are turned sideways for pick-up by jack ladders (not shown) for feeding through the ponds ll. The pick-up ladders grip the logs and drag them through the bottom of the ponds l1.
Hot water in the ponds ll cleans the logs of any dirt and ice. The logs are then spilled into a gutter (not shown~
for turning, so that the legs can he fed lengthwise through debarkers 12. Following debarking, the logs are moved to a slash deck 14. The slash deck 14 includes a pluraiity of circular saws 15 spaced apart by a distance of two feet so that each log is cut into two foot or smaller lengths.
The short logs are moved sideways into flakers 16 for flaking to product wafers of the dimensions required for board making. If the plant is producing waferboard, the wafers should be approximately two inches. Each wafer is flat, resembling a small piece of thin veneer, with a grain running in the plane of the wafer. In the case of so-called oriented strand board, the length of each strand is approximately three to four inches, the width is approximately three-quarters of an inch and the thickness and the other characteristics are the same as for wafers.
WAFER TREATMENT
The wafers thus produced are fed through a ~;Z70~;94 vibraling screen separator 18 for se~-~aratiorl of lln(3esir,l~)le small particles. The small particles are discharged through outlet 19 to waste. The remainder of the flakes are conveyed t,~lrough dryers 20 for reducing the moisture content to approximately four percent.
Alternatively, as best shown in Fig. 2, the wood chips are fed into storage bins 21, and discharged via a feed hopper 23 and a screw feeder 24 to a streaming tube 25 for softening of t,he wood flakes. Chemicals can be added to the tube 25 to accelerate the cooking (softening) process.
When the flakes have been cooked sufficiently, they are transferred by screw conveyors 28 to a twin stream pressurized refiner 29, which is operated by a drive motor 30. Wood fibre leaving the refiner 29 is fed via conveyor 31 into a cyclone separator 32 where fibre is separated from liquid, and the fibre is fed into the dryers 20.
Regardless of the type of product being produced, the wafers or fibre (hereinafter referred to simply as flakes) are fed through a cyclone 33 and dropped onto a conveyor belt 34 for flame retardant treatment at 36. Flame retardant liquid is sprayed onto the flakes on the conveyor belt 34 to achieve the desired retardant content. The flakes are again dried in dryers 37, fed through a cyclone 38 to a storage area 39 to ensure that the moisture content is consistent throughout -the stored flakes. The cyclones 33 ~7(~ 4 and 38 decrease the spee(3 of n~ovelner)t c,f the f]akes, so thilt they can drop by gravity.
The flakes move from the storage area 39 through a vibrating dry screen separator 40 where small particles are removed and discharged through an outlet 42 to waste. The flakes having the correc-t dimensions are coated with a wax/plasticizer mixture at 43, and then with a phenolic resin in a blender 45. The plasticizer, e.g. glycerine is applied first, and a paraffin wax is then applied so that the powdered plastic resin can attach to the flakes. The flakes are then moved by a conveyor 46 to forming heads 47.
PRODUCT FORMATION
The forming heads 47 deposit the required quantity of flakes on a conveyor belt 48 in the correct proportions and thicknesses. The heads 47 align the flakes lespecially in the case of oriented s-trand board) so that longitudinal axes of the flakes in the first layer are aligned with the direction of conveyor belt travel, the flakes of the second layer are perpendicular to the flakes of the firs-t layer, and the last layer flakes are aligned with the first layer flakes. The operation of each forming head 47 is controlled by computerized thickness and weight detec-tors 4~. The final thickness of the mat thus produced is governed by the speed of the conveyor belt 48. The slower the speed of the belt, the thicker the mat. The mat of thus oriented flakes lZ7~ 4 is fed on the conveyor belt 48 thrc-ugh an endless c~h;llrl press ger.erally indicated at 5U. for such purpose, the conveyor belt 48 passes around rollers 51 to define an endless path a portion of which includes the press 50.
PRESS
The press 50 is intended to subject the mat to a pressure of up to 500 lbs. per square inch at a temperature of up to 400F. Referring -to Figs. 3 and 4, the press 50 includes a pair of skeletal frames 52 and 53. The lower frame 52 includes sides ~one shown~ defined by legs 54 and top bars 56 interconnected by a plurality of crossbars 57.
The upper frame 53 includes sides defined by tubular legs 59, a top bar 60 and crossbars 61 extending therebetween.
The legs 59 are slidably mounted on posts 62 extending upwardly from the top bars 56 of the lower frame 52. Thus, the legs 59 and the posts 62 define piston cylinder devices for adjusting the distance between the top bars 56 and 60.
The frames 52 and 53 carry lower and upper endless chain assemblies 64 and 65, respectively. Each chain assembly 64 or 65 is defined by a plurality of transversely extending, pivotally interconnected con-tainers 66, which are filled with a fluid which can be heated to a temperature of 400F.
As shown in Fig. 4, each of the containers 66 includes an elongated casing 67 defined by a top wall 68, a bottom wall 69, side walls 70 and 71 and a pair of end walls lZ7~94 (not-, sllc)wll). Rectangu],ar, vl-~rticdl parti-tions 72 dnd 73 ,lr~, provided in the casing 67 for strengthening t~le container.
Bearings 74 are plovidecl on the side walls 70 and 71 for receiving a metal shaft (not shown) for rotatably interconnecti,ng adjacent containers. Fins 75 extend outwardly from an inclined -top portion of one side wall 70, and fins 76 extend outwardly from the inclined top portion of the other side wall 71. The fins 75 are staggered with respect to the fins 76, so that the fins can overlap each other to main-tain the containers 66 in alignrnent. Wells 77 are provided in the top of each container 66. The wells 77 are defined by a base 78, the inclined top ends 79 of the side walls 70 and 71, and end walls 80 (one shown). The flanges 81 are provided at the ends of the wells 77. The flanges 81 are thick and rounded for defining bearing plates. The fluid in the containers 66 is heated by top and bottom catalytic heaters 82 and 83, respectively. The lower chain assembly 64 passes around a driver drum 84 and an idler drum 85. Each of the drums 84 and 85 includes outwardly -taE~ering teeth or sprockets 86 for engaging the wells 77 in the top wall 69 of -the containers 66 for driving the chain assembly 64. The rounded bearing plates 81 facilitate movement of the teeth 86 into and out of the wells 77. Similarly, the upper chain assembly 65 passes around a driven drum 89 and an idler drum 90, each of which g 127~ 34 inCllldeS I eet-~l OVet' the entire periphery thereof for engaging the con-tainers of the upper chain assemb].y 65. T}lf drums 84 and 89 are drl.ven in synchronism, i.e. at the same speed.
The lower chain assembly 64 is supported dwring movement between the bottom of the drums 84 and 85 by spaced apart, transversely extending rollers 92 mounted on legs 93.
Similarly, the upper chain assembly 65 is supported during movement between the top of the rollers 89 and 90 by rollers 95 extending transversely between legs 96 mounted on the upper frame 53. The top run of the lower chain assembly 64, i.e. the portion of the lower chain assembly moving between the top of the drums 84 and 85 is supported by a plurality of parallel, longitudinally extending rows of wheels 98 (only part of one row shown in Fig. 3). The wheels 98 are mounted individually on posts 99 extending upwardly from the lower frame 52. As best shown in Fig. 5, wheels 98 extend across substantially the entire width of the chain assembly 64. A similar set of wheels 101 is mounted for vertical adjustment between arms 102 extending downwardly from the upper frame 53 for bearing against the bottom run of the upper chain assembly 65 between the drums 89 and 90~
Mat carried by the lower conveyor belt 48 into the press 50 is sandwiched between such lower conveyor belt and an upper endless conveyor bel-t 104, which passes around :1~7(~ 4 roll~-~rs l05 arc)llrld t:he upper ~fr-ame ~3, the (IpE~er ch~Airl assembly 65 and the heater 82. The use of two c-Jnveyor belts 4O and 10~ between the endless chain assemblies 64 arlf~
65 prevents slipping of the wood material during passage through the press 50. The leading end of the upper chain assembly and of the conveyor belt 104 are inclined at 2 to the horizontal so that -the material path into the press 50 tapers inwardly until achieving the desired thickness of material which is maintained until the sheet is discharged frorn between the conveyor belts 48 and 104. The dwell time in the press 50 is sufficient -to heat the entire mat and activate or catalyze the adhesive.
FINAL PRODUCT FORMATION
The product discharged from the press 50 is an endless sheet 105 of oriented strand board, which can be cut into lengths 106 at 107, cooled at 108, graded at 10~ and passed to storage 110.
Alternatively, if the sheet is to be other than flat, the adhesive mixed with the wood strands or flakes contains two catalysts. One catalyst is activated by heat and pressure in the press 50. The board discharged from the press 50 is sufficiently rigid to support itself and maintain its thickness, but is also flexible with no permanent memory. The shee-t 105 is discharged from the press 50 and fed through a conventional roll forming press 112 to impact ~27~

a desired corrllgat~e(~ con-tour 113 -to the sheet. The pr-ss 112 is operated dt a pressure of 500 psi and a temperatllre Or 400F to heat the sheet completely, and for activating the second catalyst. The press 112 Lncludes opposed upper and lower endless, stainless steel, mesh-type conveyor belts 115 and 116, and upper and lower forming rollers 117 and 118, respectively mounted in a frame 120. The conveyor belts 115 and 116 protect the product from tension induced by rollers during forming. The thus corrugated sheet 121 is fed between the rollers 122 of a finishing machine 123. The machine 123 may include microwave or ultraviolet light sources for additional sheet heating. The sheet is fed to cutting at 124 where the sheet is cut into panels 125. The panels 125 are graded at 127 and fed to storage at 128.
A third alterna-tive is to feed the sheet 105 through a forming press 130 to impart a rectangular corrugated cross-sectional contour 131 to the panel. The press 130 is like the press 112, including a frame 133 carrying opposed, endless conveyor belts 134 and 135, and forming rollers 137. Af-ter leaving the press 130, the sheet is sprayed at 138 with a vapor barrier coating. The areas receiving vapour barrier are dictated by the ultimate use of the panels produced from the sheet. The now corrugated sheet is fed through an extruder generally indicated at 140 ~descrihed hereinafter in greater detail) mounted in a ~27a55~4 frame 141 lo fc)~m triarlgular orrugatiorls. The extru-1e~ 140 is followed by counter-rotating rollers 1~2 for filling gaps between the corrugations with a hard setting filler, cooling at 144, sanding in a sander 145, veneer plaster application at 146, mechanical smoothing at 148, finishing of the plaster coating with water rnist and rollers at 149, cutting at 150 and finally storage 152.
EXTRUDER
Referring to Figs. 9 to 16, the extruder 140 is defined by an elongated casing 155 of rectangular cross section in an ultraviolet light boo-th. The sides 156 of the casing 155 are parallel at the inlet end 157, tapering in a downstream direction (with respect to product flow) in the central area 159 and parallel at the discharge end 160.
Ultraviolet lights (not shown) are provided in the casing 155 above and below the path of travel of the sheet approximately at the junction between the inlet end and the tapering central area. A plurality of parallel, longitudinally extending ridges 162 extend downwardly from the top walL 163 of the casing into gaps between corresponding ridges 164 extending upwardly from the bottom wall 165 of the casing. At the inlet end ~57 of the casing 155, the gap between the square cross section portions of the ridges 162 and 164 is large (Fig. 11) so that the already square corrugated sheet can enter the extruder. The 65~4 gap becollles prc)gressively narrower while rnairltaining the s~uare corrugations (Flg. ]2) to compress the ~heet to the desired thickness. ~ plurality of rollers 167 are provided in the top ancl hottom walls 163 and 165, respectively of the casing for pushing the product through the extruder. During movemen-t into the tapering portion of the casing, the sides of the corrugations are caused to bend towards each other (Fig. 13), i.e. the cross sectional configurations of the ridges 162 and 164 change until the corrugations form triangles (Fig. 14). A fast setting phenolic adhesive 16 (Fig. 14) is introduced through nozzles 169 (Fig. 10) to seal the gaps between the corners of adjacent triangles on each side of the sheet. At their trailing ends 170, the ridges 162 and 164 are separated from their respective top and bottom walls 163 and 165 permi-tting complete closing of the triangular corrugations.
If the corrugated sheet is to be insulated, frothed insulating foam is introduced into the corrugations via tubes 171 extending into each of the ridges 162 and 164 and nozzles 173 at the downstream discharge ends of the ridges 162 and 164. The thus produced corrugated panel is discharged through an open passage 174 at -the trailing discharge end of the casing 155.
~eferring to Fig. 17, the products of the present invention can be used in building construction -to form lZ7(~ 4 insulated walls :L76 and floors 177 contalnirlg pclnels extruded from the extruder 140. The floor panels are not plaster coa-ted. The hase Or t:he floor panels is covered with 1~2 inch orientecd strand board 179 produced in the press 50, and the top of the floor panels is covered with 5~8 inch sandecd oriented strand board 180. While it is necessary to cover the exterior of the wall panels with exterior siding 182, and interior plaster finish 183 is produced on the panels at 146 (Fig. 8).

Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An extruder for forming a reconstituted wood sheet with triangular corrugations from a flexible sheet of wood flakes and resin comprising elongated casing means;
inlet means in one end of said casing means for receiving a flexible sheet; outlet means in the other end of said casing means for discharging a finished corrugated sheet from the casing means; and passage means extending between the inlet means and outlet means, the cross section of said passage means changing from said inlet means to said outlet means, whereby the cross sectional configuration of the sheet is altered during passage through said casing means to a final configuration of alternating, contiguous, triangular corrugations.

2. An extruder according to claim 1, including first nozzle means in said casing means for dispensing adhesive into the junctions between the corners of adjacent corrugations to seal the corrugations together.

3. An extruder according to claim 2, including second nozzle means for injecting insulation into the triangular corrugations for rendering the corrugated sheet insulative.

4. An extruder according to claim 1, wherein said casing means is rectangular in cross section, including a rectangular inlet end portion, a central portion tapering downstream in the direction of sheet travel, and a rectangular outlet end portion of smaller area than said inlet end portion.

5. An extruder according to claim 4, wherein said casing means includes top and bottom walls;
longitudinally extending top projections on said top wall;
and longitudinally extending bottom projections; said bottom wall, said top and bottom projections extending into overlapping relationship to define said passage means.

6. An extruder according to claims 1, 2 or 4, including roller means in said casing means for feeding said sheet through the casing means.