Abstract
A method for manufacturing modular retaining wall blocks in natural stone, wherein the blocks are trapezoidal blocks having top and bottom surfaces with channels that receive offset connectors in multiple orientations for building upright, offset, and curved walls. Stone from a quarry is cut or split to form substantially rectangular elongate blocks having top and bottom surfaces, opposed side faces, and opposed ends. A series of channels running parallel to the side faces is cut in each of the surfaces, the top channels lying across from the bottom channels but offset therefrom. The elongate blocks are then cut between opposing pairs of channels to form trapezoidal blocks having front and rear faces.
Claims
1. A method for manufacturing a modular retaining wall block in natural stone, said method comprising the steps of providing an elongate block of natural stone having parallel opposed top and bottom surfaces, parallel opposed side faces, and opposed ends; cutting a plurality of rectilinear bottom channels in said bottom surface, each said bottom channel being parallel to said side faces; cutting a like plurality of rectilinear top channels in said top surface, each said top channel being parallel to said side faces and facing oppositely from a respective said bottom channel; and cutting each said elongate block to form a plurality of trapezoidal blocks, each said trapezoidal block having trapezoidal top and bottom surfaces with respective said top and bottom channels therein, opposed front and rear faces formed in alternation in each said side face, and opposed end faces, wherein each said bottom channel is offset from the oppositely facing top channel toward one of said front and rear faces.
2. The method of claim 1 further comprising providing a flat rectangular slab of stone having parallel top and bottom surfaces; and splitting the slab to form a plurality of said elongate blocks, at least one side face of each said elongate block being formed by said splitting.
3. The method of claim 1 wherein said front faces are larger than said rear faces.
4. The method of claim 3 wherein said bottom channels are offset toward said front faces.
5. The method of claim 1 wherein said top channels are centered between said side faces, whereby said top channels of centered between said front and rear faces.
6. The method of claim 1 wherein said channels are discrete channels that do not extend to said end faces of said trapezoidal blocks.
7. The method of claim 1 wherein said channels are cut by routing.
8. The method of claim 7 wherein said routing is performed by a router on a bridge.
9. The method of claim 1 wherein said channels are cut in each of said top and bottom surfaces sequentially.
10. The method of claim 9 wherein said elongate block is flipped after cutting the channels in one of said top and bottom surfaces, whereupon the channels are cut in the other of said top and bottom surfaces.
Description
BRIEF DESCRIPTION OF THE DRAWING
[0028] FIG. 1A is a plan view of the top surface of a block;
[0029] FIG. 1B is a plan view of the bottom surface of a block;
[0030] FIG. 1C a section view taken along the line C-C of FIGS. 1A and 1B;
[0031] FIG. 2A is a top perspective of a connector;
[0032] FIG. 2B is a bottom perspective of a connector;
[0033] FIG. 2C is a sectioned perpective of a connector;
[0034] FIG. 3 is a perspective of a modular block with assymetric connectors having first portions received in the first channel so that their second portions extend toward the front face of the block;
[0035] FIG. 4 is a perspective of a modular block with assymetetric connectors having first portions received in the first channel so that their second portions extend toward the rear face of the block;
[0036] FIG. 5A is a perspective of a freestanding wall;
[0037] FIG. 5B is a plan view of the freestanding wall of FIG. 5A;
[0038] FIG. 5C is a section taken along line C-C of FIG. 5B;
[0039] FIG. 5D is a section taken along line D-D of FIG. 5B;
[0040] FIG. 6A is persective of a vertical retaining wall;
[0041] FIG. 6B is a plan view of the vertical retaining wall of FIG. 6A;
[0042] FIG. 6C is a section taken along line C-C of FIG. 6B;
[0043] FIG. 7A is a perspective of a setback retaining wall;
[0044] FIG. 7B is plan view of the setback retaining wall of FIG. 7A;
[0045] FIG. 7C is a section taken along line C-C of FIG. 7B;
[0046] FIG. 8 is a plan view of a curved setback retaining wall with half bond courses;
[0047] FIG. 9 is a plan view of a curved setback retaining wall with quarter bond courses;
[0048] FIG. 10 is a schematic showing the steps in manufacturing the modular wall blocks from a quarry block; and
[0049] FIG. 11A is a top plan view of three blocks after the final cut;
[0050] FIG. 11B is a bottom plan view of three blocks after the final cut;
[0051] FIG. 12A is a top plan view of a series of molded concrete blocks according to an alternative embodiment; and
[0052] FIG. 12B is a bottom plan view of the blocks of FIG. 12A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0053] FIGS. 1A-1C show a trapezoidal modular block 10 according to a first embodiment of the invention. Each block has parallel opposed top and bottom trapezoidal surfaces 11, 13 bounded by parallel opposed front and rear faces 16, 17 and converging end faces 18, 19. As shown in FIG. 1A, a top channel 12 is centered between front and rear faces 16, 17. FIG. 1B shows bottom surface 13 and bottom channel 14, which is wider than top channel 12 and is orthogonally across from top channel 12 but offset toward front face 16. The channels 12, 14 do not extend to the end faces 18, 19. FIG. 1C illustrates the depth of the top and bottom channels 12 and 14, which are profiled to receive respective first and second portions of a connector. The channels 12, 14 needn't be centered between the front and rear faces 16, 17; the operative factor in determining setback is the offset of the bottom channel 14 from the top channel 12.
[0054] FIGS. 2A-2C show a preferred embodiment of connector 20 according to the invention, having a rectangular first portion 22 profiled for sliding reception in a top channel 12 of a block 10, and a cylindrical second portion 24 profiled for sliding and rotatable reception in a bottom channel 14 of the block. The connector 20 is preferably injection molded in nylon and has cavities that minimize the amount of material used in production. The second portion has a slightly oval cross-section for the same reason; it incorporates less material than a round cross-section, but still permits rotation.
[0055] FIGS. 3 and 4 show connectors 10 with their first portions 22 placed in the top channel 12, also referred to as the receiving channel. In FIG. 3 the second portions 24 are oriented toward the front face 16. Since the second channel 14 is offset toward the front face of the block, this orientation is suitable for a vertical wall (FIGS. 6A-6C). In FIG. 4 the second portions are oriented toward the rear face 17; this orientation is suitable for a setback wall (FIGS. 7A-7C).
[0056] FIGS. 5A-5D show a freestanding wall, so-called because it is constructed with front and rear faces 16, 17 alternating in each course so that no gaps are present. Connectors 20 are placed with opposed orientations in the top channel 12 of each block, with one second portion 24 received in the bottom channel 14 of one overlapping block 10, and the other second portion 24 received in the bottom channel 14 of another (oppositely facing) overlapping block 10.
[0057] FIGS. 6A-6C show a vertical retaining wall, so-called because it is constructed with front faces 16 all on one side in every course, so that gaps are present between all rear faces 17 in every course. These gaps will be filled with soil being retained behind the wall. All connectors 20 are oriented with their second portions 24 extending toward the front faces 16, so that the front faces 16 of successive courses are coplanar when the second portions 24 are received in the second channels 14 of the next course.
[0058] FIGS. 7A-7C show a setback retaining wall, which is also constructed with front faces 16 all on one side in every course, so that gaps are present between all rear faces 17 in every course. However now all connectors 20 are oriented with their second portions extending 24 toward the rear faces 17, so that the front faces 16 of the upper course are set back from the front faces 17 of the lower course when the second portions 24 are received in the second channels 14 of the next course.
[0059] FIGS. 8 and 9 illustrate a curved setback retaining wall, utilizing an alternative embodiment of modular block 30 having top and bottom trapezoidal surfaces 31, 33, front and rear faces 36, 37, and top and bottom channels 32, 34 extending to the end faces 38, 39, somewhat simplifying manufacture. The end faces 38, 39 are placed flushly together and connectors 20 are placed with their second portions 24 oriented toward the rear faces 37, with any desired amount of overlap between courses. The top channel in the top block and the bottom channels in the bottom blocks are not shown to avoid visual clutter, but are nevertheless present; all three blocks 30 in each figure are identical. FIG. 8 shows a half bond overlap, whereas FIG. 9 shows a quarter bond overlap. This may be continued to form an arc of any desired length, or alternated with straight sections of vertical retaining wall to form a bend. The blocks may also be placed to form a concave curve wherein the gaps between rear faces are larger than in a straight retaining wall.
[0060] From the foregoing it will be apparent that many permutations of the illustrated arrangements are possible. For example, a retaining wall may be constructed vertically for two courses, then setback for two courses, forming steeper steps in the wall.
[0061] FIG. 10 illustrates the manufacturing process. An 844 quarry block 40 is cut into 846 flat slabs 41 at the quarry for delivery to a local fabricating facility, where ensuing operations are performed. A flat slab 41 is loaded onto an infeed conveyor 44 that moves it to the hydraulic stone splitter 46, where it is split into 496 blocks 42. Each long block 42 is transferred by indexing conveyor 48 at loading station 52 and moved to cutting station 53, where a router on bridge 50 cuts second (bottom) channels 14 to provide the desired setback in a finished wall. The stick is then flipped at station 54 and returned to cutting station 53, where the first (top) channels 12 are routed. The blocks 42 are then cut by a mitre saw on the bridge 50 to form angled end faces 18, 19 framing trapezoidal surfaces 11, 13; scraps from the ends simply fall into bins. As shown in FIGS. 11A and 11B, this yields a series of three nested blocks 10 in the final trapezoidal shape, with features numbered as in FIGS. 1A-1C. A robot 56 picks up the fully cut block 42 at station 54 and loads it onto a pallet 58 on outfeed conveyor 57; pick-up may be accomplished by a vacuum gripper of the type made by Schmalz, Inc. of Raleigh, N.C.
[0062] As will be apparent to one skilled in the art, many variations and substitutions in the manufacturing method are possible. For example the slabs 41 may be split at the quarry to form blocks 42, eliminating the need for a splitter at the local fabricator. A multi-function fully automated tool, for example a Sasso K600 5-axis CNC bridge saw, may be substituted for the router and miter saw on a bridge. The equipment chosen may ultimately depend on cost considerations dictated by the scale of production.
[0063] While the invention is focused on modular blocks that can be fabricated in stone, the inventive shape(s) can also be realized in concrete that is molded or cast. This opens the possibility of achieving shapes that cannot be realized with straight cuts. For example, as shown in FIGS. 12A and 12B, concrete blocks 60 can be formed with opposing convex and concave end faces 68, 69 with semicircular profiles so they can be placed together in series to form any desired curvature in a wall without gaps. As shown here, the top and bottom channels 62, 64 are formed in respective top and bottom surfaces 61, 63 adjacent to respective front and rear faces 66, 67 on opposite sides of a central cavity 65. When the channels in successive courses are aligned, their convex ends will point in opposite directions. If there were no central cavity, the channels could be formed in any desired position.
[0064] The foregoing is exemplary and not intended to limit the scope of the claims which follow.
