Abstract:
The present invention relates to an apparatus and method for forming molded tapered products, such as masonry blocks, whereby high quality finished products are removed from their mold without the need for complex machinery for demolding. The mold may include one or more mold cavities having one or more movable cavity walls. The movable cavity walls may include an end liner having a planar product forming surface capable of moving from a vertical position to an angled position. Tapered products may be formed by moving the mold towards a pallet so that the pallet engages with the end liner and causes the end liner to move from the vertical position to the angled position. Moldable material may then be introduced into the mold cavity and may be allowed to remain in the mold cavity until it is self-sustaining. The mold may then be moved away from the pallet such that a molded product remains on the pallet, thereby allowing the end liner to move from the angled position to the vertical position.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to concrete-based product making machinery. More particularly, the invention relates to machinery for producing concrete-based products having a vertical taper, and the removal of such units from their molds. 
       BACKGROUND OF THE INVENTION 
       [0002]    Concrete masonry units are available in a wide range of sizes and shapes, and are used for a variety of applications, ranging from concrete blocks and bricks to segmented wall blocks. 
         [0003]    Generally, masonry units are produced using an automated process. The typical automated process for producing the units includes placing a mold, which is open at the top and bottom, on a solid pallet. The mold is then filled with a suitable composite material (generally comprising concrete and aggregate material). Next, the filled mold and/or pallet may be vibrated while the material is simultaneously compacted within the mold using a compression head inserted into the top of the mold to increase the density of the composite material. The molded composite material may then be stripped from the mold (while still resting on the pallet) and cured to form a building unit such as, but not limited to, a brick or a paver block. 
         [0004]    Often, it is desirable to produce masonry units having at least one tapered vertical edge (e.g., the width of the top of unit is different from the width of the bottom of the unit). These masonry units are generally produced using a mold having one or more angled side walls. However, stripping the molded composite material from these molds is difficult because the side walls must be moved away from the composite material before the molded unit may be removed from the mold. Therefore, special molds are typically used to create tapered masonry units. 
         [0005]    One prior attempt at creating tapered masonry units has been to use a “tilt-over” mold, such as the apparatus described in U.S. Pat. No. 4,735,562 to Boutellier. Tilt-over molds are inverted during the filling and forming process and are then turned over to remove the molded unit. However, tilt-over molding requires complex machinery and results in longer production times. Further, turning the mold upside down can damage the inverted face of the finished unit, which is typically not completely cured during the de-molding step. Because damaged units are normally rejected, manufacturing prices are increased. 
         [0006]    Another technique involves the use of a mold having product-forming walls that may be retracted away from the molded unit. Such retractable walls are typically actuated in multiple directions by hydraulically and/or pneumatically operated machinery which may be bulky and which may require separate power and controls. Such arrangements add complexity and cost to the manufacturing process. They also reduce the usable mold space, thereby yielding fewer finished units per manufacturing cycle. 
         [0007]    Yet another attempt at creating tapered masonry units has been to use hinged walls which are pivotally connected at a point within the mold cavities. In this technique, as the mold is placed on a pallet, the walls may be forced into an angled position, thereby creating a mold having a tapered edge. However, this technique has been found to be unsuitable because the hinged walls may pivot out of position during the vibrating step discussed above. As a result, the tapered walls of the masonry product may become deformed and unusable. 
         [0008]    Therefore, a less complex, cost-effective apparatus and method for creating high quality tapered products is desirable. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention relates to concrete-based product making machinery. More particularly, the invention relates to machinery for producing concrete-based products having a vertical taper, and the removal of such units from their molds. 
         [0010]    One embodiment of the present invention includes a mold for forming a molded product having at least one tapered wall. The mold may comprise a frame and at least one mold cavity, the at least one mold cavity having a plurality of cavity walls defining the sides of the mold cavity, and the at least one mold cavity having an open top through which moldable material can be introduced into the mold cavity. The at least one of the plurality of cavity walls may be a movable wall comprising a stationary element having a groove and being attached to the frame, a pivot element, the pivot element being rotatably attached to the stationary element, and a movable element having a planar product forming surface. The movable element may be slidably and rotatably attached to the groove of the stationary element and the movable element may be rotatably attached to the pivot element such that the movable element is capable of moving between a first position and a second position. 
         [0011]    Another embodiment of the present invention may include a method of forming a tapered molded product with a mold. The method may include the step of moving a mold towards a pallet, the mold comprising a frame and at least one mold cavity, the at least one mold cavity having a plurality of cavity walls defining the sides of the mold cavity, and the at least one mold cavity having an open top through which moldable material can be introduced into the mold cavity, wherein at least one of the plurality of cavity walls is a movable wall, the movable wall including a stationary element attached to the frame, the stationary element having a groove, a pivot element, the pivot element being rotatably attached to the stationary element, and a movable element having a planar product forming surface, the movable element being slidably and rotatably attached to the groove of the stationary element and the movable element being rotatably attached to the pivot element, such that the movable element is capable of moving between a first position and a second position. The method may also include the steps of engaging the pallet with the movable element such that the pallet forces the movable element from the first position to the second position, introducing a quantity of moldable material into the at least one mold cavity while the movable element is in the second position, allowing the moldable material to remain in the at least one mold cavity until it forms a self-sustaining molded product while the movable element is in the second position, and moving the mold away from the pallet such that the self-sustaining molded product remains on the pallet and the movable element moves from the second position to the first position. 
         [0012]    These and other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed the same will be better understood from the following description taken in conjunction with the accompanying drawings, which illustrate, in a non-limiting fashion, the best mode presently contemplated for carrying out the present invention, and in which like reference numerals designate like parts throughout the Figures, wherein: 
           [0014]      FIG. 1  is a top view of a mold assembly according to one embodiment of the present invention. 
           [0015]      FIG. 2  is a side view of a mold assembly according to one embodiment of the present invention. 
           [0016]      FIGS. 3A and 3B  are side views of a single mold cavity according to the present invention. 
           [0017]      FIGS. 4A to 4E  illustrate the method of use and operation of the end walls  28  to form a tapered product according to one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    The present disclosure will now be described more fully with reference to the Figures in which various embodiments of the present invention are shown. The subject matter of this disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. 
         [0019]      FIG. 1  is a top view of a mold assembly A and  FIG. 2  is a side view of mold assembly A according to one embodiment of the present invention. As illustrated in the Figures, mold assembly A may include a frame  10 . The frame  10  may include side brackets  12 , center bars  14  and end bars  16 . The side brackets may be connected to center bars  14  and end bars  16  using any conventional means for attaching two mechanical elements including, but not limited to, bolting, welding, gluing and screwing. A center cover plate  18  may be attached to center bars  14  and an end cover plate  20  may be attached to each end bar  16 . Division plates  22  may be attached through the center cover plate  18  and the end cover plates  20  to define fixed, parallel side walls  24  of mold cavities  26 . The end walls  28  of each mold cavity  26  may be defined by movable end liners  340  and  345  having product forming surfaces  341  and  346 , as discussed in detail below with reference to  FIGS. 3A and 3B . 
         [0020]    In one embodiment of the present invention, the various elements of mold assembly A may be manufactured from any material having sufficient strength to withstand the forces associated with the production of molded masonry units. This may include, but is not limited to, steel, titanium, carbon fiber, composite materials, carbide, ceramics or other common materials known to one of skill in the art. 
         [0021]    It should be noted that each side wall  24 , end wall  28  and mold cavity  26  is not labeled in  FIGS. 1 and 2 . However, the embodiment illustrated in  FIGS. 1 and 2  includes eighteen mold cavities  26 . Further, it is contemplated that mold assembly A may be configured to have any number of mold cavities in any configuration to increase or decrease the number of tapered masonry units simultaneously produced by a mold assembly. It should be noted that this includes a mold assembly A having only a single mold cavity  26 . 
         [0022]    In one embodiment of the present invention, a hanger  30  may be connected to each side bracket  12 . The hanger  30  may facilitate movement of the mold assembly A by production machinery (not shown). While a hanger  30  is illustrated in the FIGS., it is contemplated that any means for attaching mold assembly A to production machinery (not shown) is contemplated including, but not limited to, bolting, welding, screwing, hydraulic clamping and air clamping. 
         [0023]    Additionally, mold assembly A may include a guide pin  32  located on one or both side brackets  12  which may facilitate alignment of mold assembly A in relation to other equipment, as is well known to those of ordinary skill in the art. Alternatively, side brackets  12  may be provided with bolt holes or keyways to facilitate handling and alignment. 
         [0024]      FIGS. 3A and 3B  are side views of a mold assembly according to one embodiment of the present invention. The various elements illustrated in  FIGS. 3A and 3B  may be manufactured from any material known in the art and having sufficient strength to withstand the forces associated with the production of molded masonry units. This may include, but is not limited to, steel, titanium, carbon fiber, composite materials and ceramics. 
         [0025]    In one embodiment of the present invention, a mold assembly may include back plates  305  and  310 , as illustrated in  FIGS. 3A and 3B . Each back plate  305  and  310  may include a slot or channel  301  and a pivot point  302 . Further, each back plate  305  and  310  may be affixed to an end bar  16  or a center bar  14  of frame  10 . 
         [0026]    A mold assembly according to the present invention may also include linkages  320  and  325 . Each linkage  320  and  325  may include pivot points  302  and  321 . As illustrated in  FIGS. 3A and 3B , linkages  320  and  325  may be rotatably attached to one of the back plates  305  or  310  at pivot point  302  using any conventional means for rotatably attaching two points including, but not limited to, the use of screws, pins or rivets. Linkages  320  and  325  may also be rotatably attached to one of the end liners  340  or  345 , as discussed below, at pivot point  321  using any conventional means for rotatably attaching two points including, but not limited to, the use of screws, pins or rivets. 
         [0027]    A mold assembly according to the present invention may also include cams  330  and  335  and end liners  340  and  345 , as illustrated in  FIGS. 3A and 3B . Each end liner  340  and  345  may include an attachment point  347  and a pivot point  321 . Further, each end liner  340  and  345  may include a product forming surface  341  or  346 . In one embodiment, product forming surfaces  341  and  346  may be planar surfaces. However, it is contemplated that the product forming surfaces  341  and  346  may be any type of surface including, but not limited to, textured, rounded, ridged or any other surface known to one of skill in the art. 
         [0028]    Further, in one exemplary embodiment of the present invention, the product forming surface may have a rectangular shape measuring approximately 100 mm by approximately 150 mm. However, it should be realized by one of ordinary skill in the art that any shape or dimensions may be utilized depending on the type of tapered block to be formed. 
         [0029]    As illustrated in the FIGS., each cam  330  or  335  may be rotatably attached at point  347  on end liner  340  or  345  and may be configured to slidably engage slot  301  in one of the back plates  305  or  310 . Each end liner  340  and  345  may also be rotatably attached to one of the linkages  320  or  325  at pivot point  321  using any conventional means for rotatably attaching two points including, but not limited to, the use of screws, pins or rivets. 
         [0030]      FIGS. 3A and 3B  illustrate a split sectional view of a mold cavity  26  taken along Line  3 - 3  in  FIG. 1 . As illustrated, each end wall  28  may include a back plate  305  or  310 . Back plate  305  may be attached to a center bar  14  and back plate  310  may be attached to an end bar  16  using bolts  306  and  311 . While bolts  306  and  311  may be illustrated, it is contemplated that any conventional means for attaching two mechanical elements including, but not limited to, welding, screwing and gluing may also be used to attach the back plates  305  and  311  to the center bar  14  or the end bar  16 . 
         [0031]      FIG. 3A  illustrates a mold cavity  26  with closed end walls  28  according to one embodiment of the present invention and  FIG. 3B  illustrates a mold cavity  26  having open end walls  28  according to one embodiment of the present invention. Because the various elements of each end wall  28  are rotatably or slidably attached as illustrated in  FIGS. 3A and 3B  and as discussed above, end liners  340  and  345  may be permitted to move between a closed position ( FIG. 3A ) to an open position ( FIG. 3B ). In the closed position, as illustrated in  FIG. 3A , the product forming surfaces  341  and  346  may be configured at an angle Θ from vertical. In one exemplary embodiment of the present invention, angle Θ may be approximately 78 degrees, creating blocks having an interior angle of approximately 102 degrees. However, one of ordinary skill in the art will recognize that the various elements of each end wall  28  may be configured so that the angle Θ may have any value to accommodate the manufacture of products having sides with any angle of taper. 
         [0032]    As one of ordinary skill in the art will realize by comparing  FIGS. 3A and 3B , the movement of the end liners  340  and  345  occurs when the cams  330  and  335  slide along grooves  301 . This may cause the various elements of each end wall  28  to slide and pivot with respect to one another due to their rotatable connections, discussed above. The movement of the elements may be caused by upward forces and gravitational forces acting on the end liners  340  or  345 , as discussed below with reference to  FIGS. 4A to 4E . Furthermore, one advantage of the present invention is that, in the open position ( FIG. 3B ), the product forming surfaces  341  and  346  may be cleared of any residual product because they are held in the vertical position whereby gravity may clear the residual product. Furthermore, one of ordinary skill in the art will realize that the vertical movement of the tapered product  350  (as discussed below) will assist in clearing any residual product from the product forming surfaces  341  and  346 . Thus, the product forming surfaces  341  and  346  may not require cleaning as often as required by prior art machinery. 
         [0033]    As discussed in detail with reference to  FIGS. 4A to 4F , the mold cavity A may be configured to rest on a pallet P which may be configured to hold a molded product  350 . When the mold assembly A is not resting on a pallet P, the product forming surfaces  341  and  346  may be configured in an open configuration, as illustrated in  FIG. 3B . Because there is no surface in contact with the bottom of end liners  340  and  345 , the end liners  340  and  345  and the linkages  320  and  325  may be allowed to drop below the bottom of the mold cavity  26  (illustrated in the FIGS. as Line B 1 ) due to the gravitational force acting on the mass of the end liners  340  and  345 . As the mold assembly A is moved in the direction of Arrow V by conventional production machinery known to those skilled in the art (not shown), the bottom of the mold cavity  26  may move closer to the pallet P. When the pallet P reaches Line B2, it may begin to force end liners  340  and  345  upwards in the direction of Arrow V until the end liners  340  and  345  are in the closed configuration illustrated in  FIG. 3A . In one exemplary embodiment of the present invention, end liners  340  and  345  may be forced upwards in the direction of Arrow V when the pallet P is approximately 5.5 cm below line B 1 . In this embodiment, an additional 18 cm of movement in the direction of Arrow V may be required for a formed product to completely clear the bottom of end liners  340  and  345 . While these specific distances are provided, it should be realized that any possible distance of travel may be required depending on the size of the block to be manufactured. Additionally, in alternative embodiments, the mold assembly A may be held stationary and the pallet P may be moved upwards in the direction of Arrow V using conventional production machinery known to those skilled in the art. 
         [0034]      FIGS. 4A to 4E  illustrate the method of use and operation of the end walls  28  to form a tapered product  350  according to one embodiment of the present invention. In  FIG. 4A , the end liners  340  and  345  are illustrated as being in an open configuration, similar to the configuration illustrated in  FIG. 3B . As illustrated by the arrows in  FIG. 4A , the pallet P and the mold assembly A may be moved towards one another, as discussed above. 
         [0035]    When the distance between the pallet P and the mold assembly A is such that the pallet P begins to contact the end liners  340  and  345 , as illustrated in  FIG. 4B , the end liners  340  and  345  may be forced into a closed position, as illustrated in  FIG. 4C . Thus, the pallet P essentially closes the opening at the bottom of the mold cavity  26 , and forms the bottom wall of the mold cavity  26 . In the position illustrated in  FIG. 4C , the product forming surfaces  341  and  346  may form the side walls of the mold cavity  26  and division plates  22  (illustrated in  FIG. 1 ) may form the front and back walls of the mold cavity  26 . 
         [0036]    As illustrated in  FIG. 4D , each mold cavity  26  may then be filled with a moldable material (e.g., a composite material such as concrete) which may be permitted to remain in the mold cavity  26  until it becomes a self-sustaining molded product  350 . During this step, the pallet P or mold assembly A may be vibrated to allow the moldable material to better settle. Typically, the vibration is accomplished by setting the pallet P on a vibrating table (not shown) during manufacturing. However, it is contemplated that the present invention may be used in conjunction with any conventional means for vibrating the pallet during manufacturing. Because the product forming surfaces  341  and  346  may be configured at angle Θ, as illustrated in  FIG. 3B , the product  350  may have a negative taper, i.e., it may be narrower at the bottom (where it is supported by pallet P) than at the top. 
         [0037]    Once the molded product  350  is ready for demolding, the mold assembly A may be separated from pallet P by relative vertical movement, as illustrated by the arrows in  FIG. 4E . As this separation occurs, the upward force on pallet P on the end liners  340  and  345  may be relieved and the end liners  340  and  345  may be permitted to move both vertically and horizontally into the open position under the influence of gravity and by lateral force applied against them by product  350  as it moves downwardly relative to the mold assembly A. It should be noted that the movement of the end liners  340  and  345  is delayed when the product  350  begins to move downwardly relative to the mold assembly A due to the pivot and slide connections of the elements in the movable side walls  28 . This avoids the prior art problems associated with pivoted walls because it prevents the end liners  340  and  345  from become dislodged during the vibration step discussed above. That is, because the product  350  must move a predetermined distance in the vertical direction which is greater than the movement the product  350  would experience during vibration, the end liners  340  and  345  stay in place during the vibration step. 
         [0038]    As illustrated in  FIG. 4E , molded product  350  may remain on the pallet P as the demolding process occurs. The separation of mold assembly A and pallet P may continue until all of the molded products  350  in mold assembly A are clear of the end liners  340  and  345 . In one exemplary embodiment of the present invention, the entire process of forming and demolding a tapered block may occur in approximately fourteen seconds. However, this period may be shorter or longer depending on the type of machinery and materials used to manufacture the blocks, or the type of blocks being manufactured. 
         [0039]    The apparatus and method of the present invention thus permit simple, automatic demolding of high quality tapered molded products by separating the mold assembly A and the pallet P on which the products  350  are formed and supported. The apparatus is simple in construction, and in at least one embodiment, does not require any external power or control devices to effect movement of the end liners  340  and  345 . 
         [0040]    While the above discussion relates to molded products having two tapered edges, it is contemplated that the apparatus and method of the present invention may be utilized for forming asymmetrical molded products. For example, a mold cavity  26  may be configured to have only one movable end liner and three fixed mold walls to form an object having only one negatively tapered side. Alternatively, a molded product having more than two negatively tapered sides may be produced by utilizing a mold cavity  26  having more than two movable end liners. 
         [0041]    Furthermore, while the movement of the end liners  340  and  345  is discussed above as being effectuated by gravitational forces, it is contemplated that additional forces may be applied to the various elements of the end walls  28 . For example, a separate machine may be configured to push or pull one or more of the various elements to cause the end liners  340  and  345  to move between the open configuration (as shown in  FIG. 3B ) and the closed configuration (as shown in  FIG. 3A ). 
         [0042]    The foregoing descriptions of specific embodiments of the present invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations are possible in view of the above teachings. While the embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to best utilize the invention, various embodiments with various modifications as are suited to the particular use are also possible. The scope of the invention is to be defined only by the claims appended hereto, and by their equivalents.