Abstract:
A concrete wall block manufactured using the dry cast process includes a top surface and a bottom surface. Opposing front and rear surfaces extend between the top surface and the bottom surface. Opposing first and second sidewall surfaces extend between the top surface and the bottom surface, and between the front and rear surfaces. The front surface and the first sidewall surface have a three dimensional texture imprinted thereon. The rear surface and the second sidewall surface may be smooth. The texturing on the front and first sidewall surfaces may generally resemble natural stone.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to the manufacture of concrete wall blocks. More specifically, the present invention relates to the manufacture of concrete wall blocks using the dry-cast method wherein the blocks have two or more adjacent decorative faces.  
       BACKGROUND OF THE INVENTION  
       [0002]     Concrete blocks are used to form free standing and retaining walls. In such applications, the visible face or faces of the blocks are often provided with a textured or decorative appearance. Concrete blocks for forming walls are used in a variety of applications from small gardening applications to large-scale construction projects. Blocks are stacked in horizontal rows called courses. Multiple successive courses may be used to create a vertically rising wall of a desired height.  
         [0003]     The concrete blocks used in constructing such walls are often manufactured using the dry cast process, which uses dry-cast block machinery to form blocks at a relatively high rate of speed. In a typical dry-cast block machine, material is fed into an open top mold from the top side. The conventional mold consists of stationary sides, to define the sidewalls of the block, and an open bottom. A removable pallet is used to temporarily close the open bottom of the mold and serve as a base during the block forming operation.  
         [0004]     During manufacture, the material introduced through the open top collects on top of the pallet and is bounded by the end and side panels. A compression head is then pressed downwards under high pressure onto the material through the open top of the mold to compact the material therein. The head forces material into the mold so as to conform to the shape of the mold. The mold may also be vibrated during compaction to promote uniform compaction. The head may also be provided with one or more shoes that have relief defined therein in order to impart detail into the material that is contacted by the head&#39;s movement.  
         [0005]     After compaction and vibration, the bottom pallet drops down, the head follows the pallet and the newly made product downward while the sides of the mold remain in position, and when the product clears the bottom of the mold, the pallet moves away from the mold and another pallet moves in place to make the next product. The head returns to its original position and the feed drawer brings more material into the mold to make the next product. The molding machinery is able to cycle several times per minute.  
         [0006]     U.S. Pat. No. 5,827,015 teaches the use of conventional dry cast molding methods to form a twinned concrete slug in the molding machinery. The slug is then split into two blocks after being cured. It should be appreciated that the top surface of the finished wall block made according to the conventional dry cast manufacturing method is formed by the surface of the steel pallet. The bottom of the block is accordingly formed by the stripper shoe.  
         [0007]     The need to eject the formed blocks through the bottom of the mold used in dry cast manufacture places limitations on the ability to create a decorative front face on the block because of the sidewalls of the mold shear across the side surfaces of the block when stripped from the mold. Therefore, efforts have been made to provide for a decorative front face on concrete wall blocks.  
         [0008]     One common current method of producing a wall block with a decorative front surface is to split a cured block (or a twinned slug) so that the front surface of the block has a fractured concrete surface that looks somewhat like split rock. This is done by forming a slug in a mold and providing one or more grooves in the slug to function as one or more splitting planes. The slug is then split apart to form two or more blocks. The appearance of the face of such block is exhibited by U.S. Pat. No. D380,560. This gives the front face of structures built with these blocks some visual depth that makes the structure look more natural. The number of facets and their arrangement can be varied to provide for different looks such as shown in U.S. Pat. No. D429,006.  
         [0009]     More recent patents, such as U.S. Pat. No. 6,321,740, disclose modification of the splitter blade used in splitting the cured block to provide edges that appear more weathered. Splitting, however, adds additional production costs by requiring an additional step to the manufacturing process and results in waste material. Furthermore, split-faced concrete blocks do not sufficiently resemble natural stone to satisfy some consumer needs.  
         [0010]     Another method to make blocks that have decorative front surfaces are described in U.S. Pat. Nos. 5,078,940; 5,217,630; and 6,224,815. These patents describe a method and an apparatus for manufacturing a concrete block having an irregular surface. The irregular surface can be made to look similar to split stone. This method includes pouring uncured block material into a mold cavity and causing a portion of the material to be retained in place relative to the cavity walls when the block is removed from the cavity. The result is a somewhat split appearance for the surface, without having to perform the splitting operation. However, the block produced from this method still does not satisfactorily resemble natural stone.  
         [0011]     Other methods employed to provide for improved decorative appearance include spraying the front face of an uncured block to wash away some cement to leave exposed aggregate. Another method consists of “weathering” a cured block by tumbling it in a tumbler with tumbler chips that knock off random pieces of the block, which rounds the ends and creates a look closer to the appearance of weathered stone. These methods, however, are labor intensive and can damage the blocks, resulting in a higher overall cost of production.  
         [0012]     Commonly owned, copending application Pub. No. US 2004/0218985, which is hereby incorporated by reference in its entirety, discloses an alternative method of providing a decorative simulated natural stone face to the front surface of a block while using the dry cast manufacturing method. The molding apparatus is configured such that the front surface of the block faces up in the mold and can therefore be provided with a pre-defined decorative face because the shoe stamps or contacts it directly. This process, however, limits the ability to provide for sidewalls that deviate from conformance to the smooth vertical sidewalls of the mold box because the downward movement of the block through the mold prevents a mold with stationary angled sidewalls or relief from being used.  
         [0013]     U.S. Patent Pub. Nos. 2003/0126821 and 2003/0182011 disclose a block machine that stamps a face on the front surface of a block while also providing a tapered sidewall to the block by use of pivoting sidewalls. However, this system does not teach the ability to impart a complex decorative face on the side surfaces of the blocks. In addition, the mold must be taken apart to a degree that makes it difficult to perform maintenance or repairs of the biasing mechanisms. This difficulty can cause undesirable delays in production. Accordingly, there remains a need to provide an improved machine and method of making dry-cast concrete blocks that is maintenance friendly and can produce blocks having complex decorative patterns on at least two adjacent faces.  
       SUMMARY OF THE INVENTION  
       [0014]     The concrete wall block according to certain embodiments of the present invention provides advantageous adjacent decorative surfaces and can be manufactured using the dry cast process. Moreover, the decorative faces do not need to be formed by a secondary splitting, weatherizing or texturizing process after curing.  
         [0015]     According to certain embodiments of the present invention, a concrete wall block manufactured using the dry cast process includes a top surface and a bottom surface. Opposing front and rear surfaces extend between the top surface and the bottom surface. Opposing first and second sidewall surfaces extend between the top surface and the bottom surface, and between the front and rear surfaces. The front surface and the first sidewall surface have a three dimensional texture imprinted thereon. The rear surface and the second sidewall surface may be smooth. The texturing on the front and first sidewall surfaces may generally resemble natural stone. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0016]      FIG. 1  is a top view of a mold apparatus according to an embodiment of the present invention in a first position.  
         [0017]      FIG. 2  is a top view of a mold apparatus according to an embodiment of the present invention in a second position.  
         [0018]      FIG. 3  is a top view of a mold apparatus according to an embodiment of the present invention showing both the first and the second position.  
         [0019]      FIG. 4  is a side view of a pair of end liners and a compression head assembly according to an embodiment of the present invention.  
         [0020]      FIG. 5  is a top view of a pair of end liners and a compression head assembly according to an embodiment of the present invention.  
         [0021]      FIG. 6  is a partial perspective view of a mold apparatus according to an embodiment of the present invention.  
         [0022]      FIG. 7A  and  FIG. 7B  are top views of a floating connection according to an embodiment of the present invention.  
         [0023]      FIG. 8A  is a perspective view and  FIG. 8B  is a top view of a concrete block according to an embodiment of the present invention.  
         [0024]      FIG. 9A  is a perspective view and  FIG. 9B  is a top view of a concrete block according to an embodiment of the present invention.  
         [0025]      FIG. 10A  is a perspective view and  FIG. 10B  is a top view of a concrete block according to an embodiment of the present invention.  
         [0026]      FIG. 11A  is a perspective view and  FIG. 11B  is a top view of a concrete block according to an embodiment of the present invention.  
         [0027]      FIG. 12A  is a perspective view and  FIG. 12B  is a top view of a concrete block according to an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0028]     Referring to  FIGS. 1-3 , there can be seen a dry-cast block mold  100  according to an embodiment of the present invention. FIG. I depicts block mold  100  in the “release” or “strip” position.  FIG. 2  depicts block mold  100  in the “fill” position. Both the strip position and the fill position are shown in  FIG. 3 , with the strip position shown in dashed lines and the fill position shown with solid lines.  
         [0029]     Dry-cast block mold  100  is generally comprised of a pair of side bars  102 ,  104  and a pair of side plates  106 ,  108  that define an open interior region. Division plates  110  span side bars  102 ,  104 , creating multiple mold cavities  112 . A front end liner  114  and a rear end liner  115  are disposed in each mold cavity  112 . One of skill in the art will recognize that the number of divider plates may be varied to increase or decrease the number of mold cavities, and accordingly, the respective number of end liners.  
         [0030]     Front end liners  114  are connected and controlled by a front end liner connector assembly  116 . Front end liners  114  are each connected to a front end liner push member  120 . Front end liner push members  120  are coupled to one another by a front end liner push bar  122 , to which each front end liner push member  120  is connected with a fastener  124 . An actuator attachment member  126  and floating connector  128  are also connected to front end liner push bar  122 . An actuator  144  attached to actuator attachment member  126  can therefore control all front end liners  114  simultaneously.  
         [0031]     Rear end liners  115  are actuated by a rear end liner connector assembly  118 . Rear end liners  115  are connected to rear end liner push members  130  which are linked to one another by a rear end liner push bar  132  to which they are attached with fasteners  134 . Rear connector members  136  are similarly attached to rear end liner push bar  132  and run along side plates  106 ,  108  where they connect to a connector bar  140 . Also attached to connector bar are two actuator attachment members  140  with floating connectors  142  to which actuators  145 ,  146  can be attached to control movement of rear end liner connector assembly  118 . Actuators  145 ,  146  attached to actuator attachment members  140  can therefore control all rear end liners  115  simultaneously.  
         [0032]     Referring to  FIGS. 4 and 6 , each front end liner  114  is also attached to a pair of guide members  121  that are aligned parallel to end liner push members  120 . Similarly, each rear end liner  115  is attached to a pair of guide members  131 . Guide members  121 ,  131  are function to maintain the alignment of end liners  114 ,  115  and to resist rotational forces throughout the molding process.  
         [0033]     Mold box  100  will generally rest in the strip position shown in  FIG. 1  when the machine is idle. The machine is moved into the fill position depicted in  FIG. 2  so that it can be filled with dry-cast concrete mixture. This is done by actuating a front end liner actuator  144  attached to front end liner connector assembly  116  that pushes front end liners  114  forward towards the middle of cavities  112 . Rear actuators  145 ,  146  attached to rear end liner connector assembly  118  also pull rear end liners  115  forward towards the middle of cavities  112 . The mold cavities  112  are then filled with mold material and the actuators  144 ,  145 ,  146  hold the end liners  114 ,  115  in place while the mold is filled, vibrated and compacted. When the mold material is stripped from the mold, front end liners  114  are pulled back and rear end liners  115  are pushed back to the strip position by their respective actuators  144 ,  145 ,  146 .  
         [0034]     Actuators  144 ,  145 ,  146  move front end liners  114  and rear end liners  115  in opposite directions at the same time. Front actuator  144  and rear actuators  145 ,  146  are thus operated out of phase from one another, because while one end liner set is pushed the other is pulled. Front actuator  144  is preferably a core puller, such as those sold by Besser Company of Alpena, Michigan. The normal stroke of such a core puller, which is about 19 inches, is limited by a mechanical stop  148  which confines the core puller&#39;s stroke to about 2 inches. Rear actuators  145 ,  146  are preferably  2 ” air cylinders attached to the core puller&#39;s frame. One of skill in the art will recognize that numerous other front and rear actuators may be used, for example, hydraulically actuated cylinders or other pneumatically actuated cylinders. Gear or linkage based actuators may also be used without departing from the scope of the present invention.  
         [0035]     Referring to  FIGS. 4 and 5 , the outside edges of the head shoe  154 ,  156  of the head assembly  150  are given cooperating relief to the top portion of the faces of each pair of end liners  114 ,  115 . This configuration allows both the head shoe  152  and the end liners  114 ,  115  to fully contact the mold material, and thus impart a higher quality face, when the end liners  114 ,  115  are in the fill position and the head shoe  152  is being used to compress the material. It will be appreciated that the use of both a head shoe and end liners to provide a face to the block allows a block to be produced that has a decorative appearance on as many as three consecutive sides.  
         [0036]     End liners  114 ,  115  may be used to either impart a decorative pattern or to provide a taper to the block sides as the user desires. Although depicted in  FIGS. 4 and 5  as having tapered end liners  115  on one side and faced end liners  114  on the other, mold box may have identical end liners on both of its ends. In one preferred configuration, a smooth non-tapered end liner is used on one side while the opposing end liner includes three dimensional relief to imprint three dimensional texture in the side face adjacent to the top face. It should be appreciated that a portion of the side of the head shoe  152  may need to be provided with complimentary relief to conform to the relief in end liner  114 . Otherwise, a tight tolerance between the head shoe  152  and end liner  114  will not be possible and material may undesirably flow into the gap formed therebetween during the forming process.  
         [0037]     End liners  114 ,  115  can provide decorative appearances with greater detail and relief than can be provided using conventional techniques, such as splitting and tumbling. Such decorative appearances include broken rock, stacked rocks, natural stone, brick, striated or roughened texture. Persons of skill in the art of concrete block manufacturing using the dry-cast process will recognize that various decorative appearances can be imparted on the front surfaces of the blocks, and that the present invention is not limited to a specific decorative facial appearance unless specifically indicated in a given Claim.  
         [0038]     To prevent concrete material from accumulating on faced end liners  114  and degrading the quality of the decorative appearance imparted to the block surface, end liners  114  may be heated. Heat is provided to end liners  114  by operatively connecting at least one heat element (not shown) to end liners  114 . Suitable heat elements include resistance elements that may be hard wired, solid state, or semiconductor circuitry. Head shoe  152  may also provided with a heat source  158 , as is known in the art. The divider plates and mold cavities may also be heated.  
         [0039]     Each actuator is connected to an end liner connector assembly by a floating connector  125  depicted in  FIGS. 7A and 7B . Floating connector  125  includes a female portion  128 , which is connected to end liner connector assembly by an attachment member  126 , and a male portion  129 , which is connected to actuator by an attachment member  127 . To connect, the male connector portion  129  simply slides into the female connector portion  128  downwardly from the top surface of female portion  129  or upwardly from the bottom surface of female portion  129 . Floating connector  125  allows for up and down vibration during the molding process, but constrains movement in the front to back and side to side directions. This holds the assembly in place to allow end liners to impart relief in the mold material, but allows sufficient motion to minimize the likelihood of failure of the connecting members.  
         [0040]     Referring to  FIGS. 8A-8B , there can be seen an embodiment of a concrete block  200  that can be made using the dry cast block mold  100  according to an embodiment of the present invention. Block  200  comprises a front surface  202  and opposing rear surface  204 , a top surface  206  and opposing bottom surface  208 , and opposing first  210  and second  212  side surfaces. Front surface  202  has a decorative appearance imparted by the head shoe because front surface  202  faces up in the mold. Side surface  212  has a decorative design imparted by either a front or rear end liner having decorative relief defined therein. End liner  114  of  FIG. 4  can be used to make the decorative side surface  212  shown in  FIGS. 8A and 8B . The opposing end liner is smooth to provide for a smooth side surface  210 . Alternatively, as shown in  FIGS. 9A and 9B , block  300  may be provided with decorative faces on front surface  302  and both first  310  and second  312  side surfaces. This is done by providing the mold with both front and rear end liners having decorative relief. A further alternative, shown in  FIGS. 10A and 10B , is to provide a block  400  with decorative side surfaces  410  and  412  and a smooth front surface  402 . In such an application, textured front and rear end liners are used while the head shoe is smooth to create a smooth front surface. The pattern given to decorative faces can vary depending on the desired appearance for a particular wall or wall section, as explained previously. Decorative faces in a particular block may have the same or different appearance.  
         [0041]      FIGS. 11A-11B  depict another embodiment of a concrete block  500  that can be made using the dry cast block mold  100  according to an embodiment of the present invention. Block  500  comprises a front surface  502  and opposing rear surface  504 , a top surface  506  and opposing bottom surface  508  and opposing first  510  and second  512  side surfaces. Front surface  502  has a decorative appearance imparted by the head shoe. Side surfaces  510 ,  512  are both tapered. Blocks with one or more tapered side surfaces are particularly adapted to create serpentine or otherwise curved walls. End liners similar to the end liner  115  depicted in  FIGS. 4 and 5  are used to make such a block  500 .  
         [0042]      FIGS. 12A-12B  depict a concrete block  600  that includes a decorative front surface  602  with an opposing rear surface  604 , a top surface  606  and opposing bottom surface  608 , and first  610  and second  612  opposing side surfaces. This block  600  is formed, however, using one textured face end liner and one smooth tapered end liner, such that side surface  612  is tapered and side surface  610  has a decorative appearance.  
         [0043]     Blocks made according to the present invention may also be provided with an interlocking extension to facilitate stacking of blocks and create a setback between courses of blocks. A mold for creating such a block is disclosed in commonly-owned copending application Pub. No. 2004/0218985, incorporated by reference above. To modify the mold of the present invention to produce blocks with protrusions in addition to multiple faces or tapers, a notch in the shape of the desired protrusion is added to the division plates as disclosed in the above publication.  
         [0044]     The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the Claims.