Method of making a hardcore honeycomb panel and honeycomb panel made thereby
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of my copending U.S. patent application Ser. No. 465,493, filed Apr. 30, 1974, now U.S. Pat. No. 3,895,144 which is a continuation in part of my application, Ser. No. 351,671, filed Apr. 16, 1973, now abandoned, which is a continuation of my application, Ser. No. 118,216, filed Feb. 24, 1971, now abandoned, the contents of all of said applications being hereby incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to hardcore honeycomb panels and methods of making such panels. 
     2. Description of the Prior Art 
     Various types of wood decorative or structural members are well known such as disclosed in U.S. Pat. No. 2,578,781 in which diagonal glued plywood board is provided in which bias-grained sheets of veneer are cut at a right angle to their edge into any desired length and two or more pieces cut in this manner are then assembled face to face so that their scissor strip joints and the grain of the wood in each alternate ply crosses at right angles. This plywood does not utilize multi-ply rhomboidal strips. The construction disclosed in this reference is purportedly more economical than conventional rectangular plywood but is not utilizable to obtain a hardcore panel without veneering, which veneering is the basis of the process in this reference. Other such prior art construction requiring the use of a veneer is disclosed in U.S. Pat. No. 1,734,826, the core being cross banded with the veneer in this reference. Other prior art compositions utilizing laminated wood to construct a multi-ply laminate, all of which are different from the invention described herein are disclosed in U.S. Pat. Nos. 2,172,093; 2,389,944; 1,214,382; 3,389,041; 677,800; 800,993; 1,994,204 and 308,184. In addition, prior art hollow doors which normally consist of a picture frame type arrangement having wood veneer on the spaced apart front and back of the door, normally utilize a honeycomb filler, such as corrugated cardboard for filling the interior space in the door. Such doors are utilized in place of more costly solid wood doors to give the same external appearances; however, such hollow doors are not as structurally sound as solid wood doors. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a hardcore honeycomb panel and a method of making this panel. The hardcore honeycomb panel comprises a plurality of adjacent batten-like members fastened together in a substantially planar configuration with each of the batten-like members having a top face, an opposed bottom face, a pair of opposed end faces and a pair of opposed side faces, each of the faces being substantially normal to the adjacent face of the batten-like member. Each of these members comprises a fastened plurality of stacked adjacent angular board segments of grained lumber, each of the segments having a top face, an opposed bottom face, a pair of opposed end faces and a pair of opposed side faces with the board segments being stacked along the longitudinal axis of the batten-like member of one end face to the opposed end face. At least a portion of the board segments define angular channels therethrough. The adjacent angular board segmet end faces are fastened together and are substantially parallel to each other with the adjacent angular board segment top, bottom and side faces, respectively. Each of the segment adjacent ends faces for every other one of the fastened batten-like members forms a predetermined acute angle, such as between 12° and 30°, with the longitudinal axis, each of the adjacent end faces comprising the batten-like members adjacent to every other member forming a predetermined obtuse angle with the longitudinal axis which is supplementary to the predetermined acute angle. The grain of each of the segments comprising a given batten-like member preferably all run in the same direction between the top surface and the bottom surface with the direction of the grain on each of the obtuse angular related segments being supplementary to the direction of the grain of each of the acute angular related segments. In making such a hardcore honeycomb panel, a multilevel stack of planar boards of grained lumber are fastened together and arranged in the stack in step-wise fashion with alternate levels comprising spaced apart board strips forming longitudinal channels in the stack sandwiched between boards having the width of the stack. The stack is cut along coplanar cut lines through the side faces thereof at the predetermined acute angle formed between the cut lines and the bottom face of the stack to provide cut portions from the stack which have rectangular top, front, bottom and rear faces and rhomboidal side faces and which have angular channels therethrough. These cut portions are further sub divided into substantially symmetrical segments which comprise the batten-like members which are alternately inverted and fastened together in the manner described above to form the honeycomb panel having angular channels therethrough. A veneer may be fastened to the top and bottom surfaces of the hardcore honeycomb panel such as to form a door. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1, 2, 3a, 3b, 3c, 4, 5, 6 and 7 are illustrative of the preferred steps in the preferred method of the present invention; 
     FIG. 7 is illustrative of a preferred embodiment of the hardcore honeycomb panel produced in accordance with this method; 
     FIG. 8 is a perspective view of an alternative embodiment of the hardcore honeycomb panel of FIG. 7 such as for use in a door structure; and 
     FIG. 9 is an exploded fragmentary perspective view of the embodiment illustrated in FIG. 8. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings in detail and initially to FIGS. 3a, 3b, 3c, 3d, 4, 5, 6 and 7, a preferred embodiment of a hardcore panel, generally referred to by the reference numeral 30, in accordance with the present invention is shown (FIG. 7). As shown and preferred in FIG. 7, the hardcore panel 30 preferably comprises a plurality of adjacent batten-like members, four such members 32, 34, 36 and 38 being shown by way of example in FIG. 7, fastened together, such as preferably with a waterproof resin such as caseine glue, or any other conventional binding adhesive, in a substantially planar configuration, as illustrated in FIG. 7. Each of these batten-like members 32 through 38, preferably has a top face, an opposed bottom face, a pair of opposed side faces, and a pair of opposed end faces, these faces being designated 32a, 32b, 32c, 32d, 32e, and 32f, respectively, for member 32; 34a through 34f, respectively for member 32; 36a through 36f, respectively for member 36; and 38 a through 38f, respectively for member 38. As shown and preferred in FIG. 7, each of the faces of the batten-like members 32 through 38 is substantially normal to the adjacent faces. The fastening together of the batten-like members 32 through 38 previously described is preferably accomplished by gluing together adjacent side faces of the batten-like members, side face 32c being fastened to side face 34d, side face 34c being fastened to side face 36d and side face 36c being fastened to side face 36d and side face 36c being fastened to side face 38d in the arrangement illustrated in FIG. 7. As shown and preferred in FIGS. 3a, 3b, 3c, 3d, 4, 5, 6 and 7, each of the batten-like members 32 through 38 preferably comprises a fastened plurality of stacked adjacent angular board segments of grained lumber, five such segments 40, 42, 44, 46 and 48 being shown by way of example in FIGS. 4 and 6. As will be described in greater detail hereinafter, each of the batten-like members 32, 34, 36 and 38 preferably includes angular through channels therein defined by the various faces of the adjacent angular board segments comprising the batten-like members so as to form the honeycomb hardcore panel 30. By way of example, member 32 includes angular channels 39 and 41, member 34 includes angular channels 43 and 45, member 36 includes angular channels 47 and 49, and member 38 includes angular channels 51 and 53, with channels 39, 43, 47 and 51 being in segment 42 and channels 41, 45, 49 and 53 being in segment 46 of the angular board segments comprising the batten-like members. These adjacent angular segments are preferably fastened together in the same fashion as adjacent batten-like members are fastened together by gluing with a waterproof resin, such as the casine glue previous mentioned. As shown and preferred, each of the segments 40 through 48 inclusive comprising each of the batten-like members 32 through 38, has a top face, an opposed bottom face, a pair of opposed end faces and a pair of opposed side faces, these faces being designated 40a, 40b, 40c, 40d, 40e and 40f, respectively for segment 40; 42a through 42f, respectively, for segment 42; 44a through 44f, respectively, for segment 44; 46a through 46f, respectively, for segment 46; and 48a through 48f, respectively, for segment 48. As shown and preferred in FIGS. 6 and 7, these board segments 40 through 48, inclusive, are preferably stacked along the longitudinal axis 50 of the batten-like member, such as batten-like member 32, by way of example, from one end 32f of the batten-like member 32 to the opposed end face 32e of the batten-like member 32. As shown and preferred in FIG. 6, segment end faces 40e, 42f, 42e, 44f, 44e, 46f, and 46e are parallel to each other, with the adjacent end faces 40e-42f, 42e-44 f, 44e-46f, 46e-48f being fastened together. End faces 40f and 48e are preferably normal to the top and bottom surfaces 32a and 32b by way of example of the respective batten-like member 32 and are produced in accordance with the preferred method of the present invention to be described in greater detail hereinafter. As is shown and preferred, the top, bottom and side faces of the fastened angular board segments 40 through 48 and the respective batten-like members 32 through 38, are fastened together to provide the planar top and bottom surfaces for the hardcore honeycomb panel 30 having angular through channels therein as well as providing the top, bottom and side faces for the respective batten-like members, with the end faces 32e and 32f being provided by cutting end faces 40f and 48e off to form a normal or perpendicular end face between the top and bottom faces 32a and 32b, by way of example, of the respective batten-like member 32. 
     As shown and preferred in FIG. 4 and FIG. 9, which are exploded views, each of the batten-like members 32 to 38, respectively, is preferably identical in structure and configuration with the exception that adjacent batten-like members are rotated 180° about the respective longitudinal axis 50 so that for batten-like members 32 and 36, by way of example, the respective end faces 40e, 42f, 42e, 44f, 44e, 46f, 46e, 48f form a predetermined acute angle 01, 02, 03 and 04, respectively (FIGS. 4 and 6) with the longitudinal axis 50 of the respective batten-like member 32 or 36 and with the angular through channels being alternately staggered at supplementary angles throughout the panel 30. Similarly, as shown in FIG. 4, preferably the alternate adjacent batten-like members 34 and 38, which are preferably identical, and the respective adjacent end faces 40e, 42f, 42e-44f, 44e-46f, and 46e-48f form a predetermined obtuse angle B 1 , B 2 , B 3  and B.sub. 4, respectively (FIG. 4), with the longitudinal axis 50, with the obtuse angle B 1  through B 4  being equal and being supplementary to the predetermined acute angle 0 1 , with 0 1 , through 0 4  being equal. Preferably, 0 1  forms a predetermined acute angle between 12° and 30° with the longitudinal axis 50 and most preferably, forms an angle of 18° with the longitudinal axis 50. Accordingly, B 1 , which is preferably supplementary thereto, forms an obtuse angle in the range of 150° to 168° and most preferably forms an angle of 162° with the longitudinal axis 50. As shown and preferred in FIGS. 4 and 6, the angular through channels 39, 41, 43, 45, 47, 49, 51 and 53 in the various batten-like members 32, 34, 36 and 38 are respectively defined by the opposed end faces 40e and 42e and the respective adjacent side faces of adjacent batten-like member angular board segments for channels 39, 43, 47 and 51 and by the opposed end faces 44e and 46e and the respective adjacent side faces of adjacent batten-like member angular board segments for channels 41, 45, 49 and 53. 
     Preferably, each of the grained lumber segments 40 through 48, inclusive, has the grain thereof running in the same direction substantially parallel to the end surfaces 40e for segment 40, 42e for segment 42, 44e for segment 44, 46e for segment 46 and 48f for segment 48. Accordingly, as shown and preferred in FIG. 4, when segments 32 and 34 are fastened together in the hardcore honeycomb panel 30, the respective grains thereof are cross-grained with the grain of member 32 running substantially at the acute angle of φ 1  and the grain of member 34 running substantially at the obtuse angle of B 1 . Similarly, the grain of member 34 is preferably cross-grained with the grain of member 38 comprising the hardcore honeycomb panel 30. If desired, however, all grains in a given batten-like member 32 through 38, need not run in the same direction from top surface to bottom surface although this is the presently most preferred embodiment. 
     As shown and preferred in FIGS. 8 and 9, the hardcore honeycomb panel 30 may be utilized in conjunction with one or more veneer layers to form a filled structure such as a door. Two such layers 70 and 72, which are preferable such as for forming a door are shown by way of example in FIGS. 8 and 9, these layers 70, 72 having a predetermined thickness and being fastened, such as by means of gluing as discussed previously, to the top face, and bottom face respectively of the hardcore honeycomb panel 30 to cover or sandwich the hardcore honeycomb panel 30 in between the respective veneer layers 70 and 72 and form the filled door-like structure. Such a configuration may be readily utilized in construction, such as, by way of example, for a door, or for a wall if desired, in which instance, if it is an interior wall in which only one side is viewed, then only one veneer layer, such as veneer layer 70 need be provided. The hardcore honeycomb panel 30 provided in accordance with the above construction provides greater structural integrity than that normally provided by a composition such as press board, such as when the hardcore honeycomb panel 30 is utilized for construction such as doors but utilizes considerably less wood than required for the panel disclosed in my previous U.S. patent application, Ser. No. 465,493, filed Apr. 30, 1974 now U.S. Pat. No. 3,895, 144. It should be noted that if a strong material such as a plastic laminate is utilized in place of veneers 70 and 72, the channels 39, 41, 43, 45, 47, 49, 51 and 53 may be wider providing a lighter honeycomb panel 30 than if a fancy wood veneer requiring more structural support to prevent cracking or puncture were utilized. 
     METHOD 
     Referring now to FIGS. 1, 2, 3a, 3b, 3c, 3d, 4, 5, 6 and 7, the preferred method of the present invention for providing the hardcore honeycomb panel 30 illustrated in FIG. 7 shall be described. Referring now to FIG. 1, a plurality of grained lumber boards 480, 484 and 488, three such boards being shown by way of example in FIG. 1, and which are all preferably of the same width, such as board seasoned to about 7 percent and heart cut, are preferably stacked in step-wise fashion as illustrated in FIG. 1 and held spaced apart at different levels by grained lumber board strips 482a, b, c and d stacked between boards 480 and 484 and grained lumber board strips 486a, b, c and d stacked between boards 484 and 488. The strips 482a-482d and 486a-486d are preferably of substantially uniform width and of the same thickness t and longitudinal extent as boards 480, 484 and 488 and are spaced apart from adjacent strips in the respective levels 482 and 484 by a predetermined distance, such as preferably the width of a strip 486a by way of example to form longitudinal channels extending between the front and rear faces of the stack. The strips 482a-482d and 486a-486d are preferably the same width and the spacing between adjacent strips in a given level, as was previously mentioned, may be varied in size dependent on the desired weight and structural integrity for the resultant hardcore honeycomb panel 30, such as by using smaller spacing if a thin fine grade wood veneer is utilized for layers 70 and 72 in the arrangement of FIGS. 8 and 9 than if a plastic laminate were utilized in place thereof, the larger the size of the channels and the greater the number thereof, the lighter the resultant hardcore honeycomb panel 30 and the fewer the number and the smaller the size, the greater the structural integrity thereof. The boards 480, 484 and 488 may be of any desired width although preferably a width of 3 to 4 inches, designated by the letter W in FIG. 1, is provided, each board preferably having the thickness t, such as, by way of example, 1/2 of an inch. Preferably, as illustrated in FIG. 1, the boards 480, 484 and 488 and strips 492a-482d and 486a-486d are identical in thickness although this is not necessary in accordance with the present invention. Each of these boards and strips is preferably planar and is rectangular in configuration. The width W of the boards 480, 484 and 488 preferably should not exceed 8 inches. These boards are fastened or bonded together, such as with a waterproof resin, such as caseine glue or any other bonding adhesive such as thermoplastic or urea adhesives in conventional fashion, such as with a horizontal-action bonding press or with high-frequency heating. The number of boards and strips alternately bonded together level by level in the step-like stack is dependent on the length of the desired hardcore honeycomb panel 30 previously described; however, as shown and preferred boards 488 and 480 form the top and bottom surfaces, respectively, of the step-like stack. Preferably, these bonded boards and strips are planed true so that the bonded joint between adjacent boards is tight from layer to layer. Furthermore, the grain of each of the boards and strips comprising the step-like multilevel stack preferably runs in the same direction such as from front face 100 of board 488 to rear face 102 of board 488 in the direction of arrow 104 illustrated in FIG. 1, the grain of boards 480 and 484 and strips 482a-482d and 486a-486d preferably being substantially parallel therewith. If desired, however, different grain directions may be utilized for the various boards and strips comprising the stack. In fastening or bonding the various boards and strips together in the stack having alternate levels of boards and strips as illustrated in FIG. 1, the stack may be placed in a conventional horizontal action bonding press and subjected to a predetermined pressure, such as 5 kilograms per square centimeter for the required pressing time of between one and two hours depending on the kind of adhesive. If desired, the stack may be taken out of the press before this time and kept under pressure thereafter with conventional clamping means. After a predetermined period of time, the stack may be cut such as with gang or band saws followed by drying out of the moisture introduced by the adhesive. As shown and preferred in FIG. 1, each of the boards and strips in the stack has a front face 100, 106, 108, respectively for boards 488, 484 and 480, and 110a, 110b, 110c and 110d for strips 486a, 486b, 486c and 486d, respectively, and 112a, 112b, 112c and 112d for strips 482a,  482b, 482c, 482d; a rear face 102, 116 and 120, respectively, for boards 488, 484 and 480, and 114a-d for strips 486a-d respectively, and 118a-d for strips 482a-d respectively, a top face 122, 126 and 128 respectively for boards 488, 484 and 480 and 124a-d, respectively, an opposed bottom face 130, 132 and 134 for boards 488, 484 and 480, respecitvely and 136a-d for strips 486a-d respecitvely, and 138a-d for strips 482a-d, respectively; and a pair of side faces 140 and 142 for board 488, 144 and 146 for board 484, 148 and 150 for board 480, 152a and 154a for strip 486b, 152c and 154c for strip 486c, 152d and 154d for strip 486d, 156a and 158a for strip 482a, 156b and 158b for strip 482b, 156c and 158c for strip 482c and 156d for strip 482d. The stack, generally referred to by the reference numeral 800, is preferably initially completely cut along a first cut line, 500 by way of example, at a predetermined acute angle φ 1 , such as preferably between 12° and 30° and most preferably 18°, between the cut line 500 and the bottom face 134 of the stack 800. As used hereinafter throughout the specification and claims, the term &#34;cut line&#34; is not meant to refer to a predetermined line marked on the surface but rather is meant to include a direction of cutting for the saw utilized, such as a conventional gang or band saw. With respect to the first cut along cut line 500, the pieces of lumber illustrated by cross hatching in FIG. 2 are preferably discarded as waste so as to provide a smooth continuous planar sloped surface having channel openings wherein as shown in FIG. 3c for the front surface of the stack 800 which slope has an acute angle φ 1 . Thereafter, the stack 800 is preferably cut along a plurality of spaced apart cut lines 502, 504, 506, 508 and 510, illustrated in FIG. 2, by way of example, at predetermined acute angles φ 2 , φ 3 , φ 4 , φ 5  and φ 6  which all preferably form the same angle between the respective cut line and the bottom face 134 on the stack, to provide a plurality of parallel sloping surfaces, these cuts preferably being completely through from one side face to the other side face of the stack to provide a plurality of substantially identical cut segments 600, 602, 604, 606 and 608 by way of example, the portion of the cut stack indicated by cross hatching between cut line 510 and the rear face of the stack 800 also preferably being discarded as waste material to provide a smooth planar sloping rear surface having channel openings therein as shown in FIG. 3c for the stack. These cut segments 600 to 608 are now preferably separable from each other and, as shown in FIGS. 3a, 3b, and 3d, each preferably comprise a pair of side faces which are rhomboidal in configuration as illustrated in FIG. 3b  whereas the top, bottom, front and rear faces thereof are rectangular in configuration, as illustrated in FIGS. 3a and 3d, with the front and rear surfaces having channel openings therein, a typical one of these cut portions 600 being illustrated in FIG. 3c. The cut portion 600, by way of example, is then preferably cut into a plurality of identical segments 620, 622, 624 and 626, four such segments being shown by way of example in FIG. 3c along a line normal to the bottom face 134 to provide a plurality of batten-like members, such as members 32, 34, 36 and 38 previously described with reference to FIG. 7. It should be noted, as shown in FIGS. 3c and 4, these normal cut lines should not coincide with the extents of the channel openings and preferably provide angular channel grooves in the batten-like members which when assembled as in FIGS. 5 and 7 form interior angular through channels 39, 41, 43, 45, 47, 49, 51 and 53. For purposes of explanation, it shall be assumed that segments 620, 622, 624 and 626 correspond, respectively, to previously described batten-like members 32, 34, 36 and 38, respectively. Each of these batten-like members is preferably identical in configuration. As illustrated in FIG. 4, and as previously described, alternate batten-like members are preferably rotated 180° about the longitudinal axis 50 as that the end faces of the adjacent batten-like members which are preferably fastened or bonded together in the same fashion previously described with reference to the bonding of the boards comprising the stack 800, with the end faces of member 32, which corresponds to segment 620 and 34, which corresponds to segment 622 providing cross graining due to the acute angle φ 1  being formed between the end faces of batten-like member 32 and the longitudinal axis 50, and the obtuse angle B 1  which is supplementary thereto being formed between the longitudinal axis 50 of member 34 and the end faces thereof, the same being true with respect to members 36 and 38 as previously described. This fastened configuration of batten-like members is allowed to dry for sufficient time, such as 24 hours, and the ends thereof are preferably cut, such as along cut lines 700 and 702 as illustrated in FIG. 5, from side face to side face of the hardcore honeycomb panel 30 as to provide a rectangular hardcore honeycomb panel as illustrated in FIG. 7. FIG. 6 illustrates the location of this cutting, by way of example, in side elevation, in which the ends are squared off for the hardcore honeycomb panel 30. Preferably, the spacing between the diagonal cut lines or planes is 7/8 of an inch, such spacing depending on the desired thickness of the final hardcore honeycomb panel 30. Furthermore, as is readily apparent from the figures, the length of the final hardcore honeycomb panel 30 which preferably comprises one batten-like member in length is determined by the height or number of boards in the stack 800. 
     It is to be understood that the above described embodiments of the invention are merely illustrative of the principles thereof and that numerous modifications and embodiments of the invention may be derived within the spirit and scope thereof.