Patent Publication Number: US-9415528-B1

Title: Concrete delivery subsystem for automated concrete fabrication system

Description:
The present application is a continuation-in-part of pending application Ser. Nos. 14/724,812 and 14/724,816 filed May 29, 2015 and Ser. No. 12/957,700 filed Dec. 1, 2010 by the same inventors. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to the field of construction, and more particularly to apparatus for manufacturing precast blocks for the construction of walls and other structures. 
     BACKGROUND ART 
     Precast concrete structural members are becoming increasingly known and used to create buildings or other structures. These precast structural members include blocks, foundation elements and partial wall units and incorporate a wide range of precast block designs that vary from the simple to the very complex. The most elementary precast block designs are those used in basic, concrete masonry, such as the well-known “cinder block”. While concrete masonry units (CMUs) may be designed for a variety of applications, they can result in structures that are structurally inferior to those created with larger, reinforced concrete units. As a result, larger precast blocks are being used, but generally the larger the precast block, the more difficult the fabrication process. 
     One example of larger-scale precast units is found in U.S. Pat. No. 5,678,903, by one of the present inventors, which discloses a modular precast wall system with mortar joints. The precast wall units discussed in this patent are of much larger size and complexity than the simple CMUs previously used. As one might expect, the sheer size and weight of larger-scale precast units present unique problems in their manufacture. If a system for their production is to be efficient, there must be a system for casting the blocks, removing the cast blocks from the casting molds and conveying them for shipment which does not require gigantic casting and transportation equipment, and which is not heavily labor intensive. 
     Thus there is a need for an apparatus and method of manufacture for larger-scale precast concrete blocks which, is substantially automated, easy to use and clean, integrates casting and transportation functions, and is of moderate scale. 
     DISCLOSURE OF INVENTION 
     Accordingly, it is an object of the present invention to provide a flexible system for manufacturing precast structural block units from concrete. 
     Another object of the present invention is to provide a modular system for creating precast units of various dimensions. 
     A further object of the present invention is to minimize the manual labor requirements, and its attendant expense, in producing precast structural members. 
     Still another object of the present invention is to provide an automated system which permits drying and hardening of the block units in a different location from the concrete pouring area. 
     Yet another object of the present invention is to provide modular mold components which may be readily substituted, for cleaning, repair and special configurations. 
     A further object of the present invention is to provide a system containing multiple self-releasing molds which are sequentially supplied by a concrete delivery system so that the system is in constant production of precast structural blocks. 
     Briefly, one preferred embodiment of the present invention is a casting machine for fabrication of precast concrete structural members which includes a self-releasing mold. The self-releasing mold includes side walls with integrally formed end dams which are movable from an open position to a closed position and a bottom casting surface, which includes pivotable bottom surfaces which rotate on bottom surface pivots to a vertical position and to a horizontal position. The bottom casting surface and side walls with integrally formed end dams surround a cavity configured to contain wet concrete. A removable bottom core completely supports a precast structural member from within when said side walls with integrally formed end dams are moved to open position. Mixed concrete is pumped into the cavity when the self-releasing mold is in closed position. The concrete is allowed to set to an initial set state, where it is rigid enough to be self-supporting, but is not yet cured. The side walls with integrally formed end dams are automatically movable to the open position when the concrete has solidified, so that the precast concrete structural member is automatically released from the self-releasing mold. 
     The casting machines are modular in nature, meaning that any number of them can be included in a precast modular system. The modular system includes a concrete mixing system in which concrete is prepared and pumped into the molds. A block transport subsystem is also included by which the initial set blocks leave the casting machines by conveyer mechanisms, and are delivered to one or more curing ovens. After initial curing, the blocks are conveyed to a stocking area for final curing and eventual shipment. 
     An advantage of the present invention is that it provides an efficient and streamlined system for manufacture of modular precast blocks. 
     Another advantage of the present invention is that it provides an apparatus of moderate size and complexity for casting modular precast blocks. 
     And another advantage of the present invention is that it provides an apparatus which includes a conveying system for the cast modular precast blocks 
     A further advantage of the present invention is that it provides an apparatus which includes a simple means of removing the cast modular blocks from the molding device. 
     A yet further advantage is that the present invention incorporates the casting, removal and conveying of the modular precast blocks in a single system. 
     Yet another advantage of the present invention is that the system is expandable to accommodate multiple casting machines, which can be served by a concrete delivery system. 
     Another advantage of the present invention is that the system can be automated so that very little human labor is required, and consequently the cost of production is reduced. 
     A further advantage of the present invention is that it can be operated as an automated system by which mixed concrete is introduced at the input and finished precast blocks can be collected from the output. 
     A yet further advantage of the present invention is that the blocks produced are created by a wet cast concrete method, which are stronger than those made by dry compaction processes, such as conventional cinder blocks. 
     Another advantage is that by producing larger blocks, there are fewer joints and cracks in a comparable expanse of completed wall than in a wall made of smaller blocks, and therefore a tighter, stronger wall is produced. 
     Additional advantages of the present invention over walls produced by the “tilt up” method, (whereby a wall section is poured on site into a horizontal mold, and is then tilted up vertically to be mounted as a wall section), are that a smooth flat surface is not required on the site, good weather is not required, wall height is not limited to a single section, and it is easier to integrate the blocks of the present invention with structural steel members with floor and ceiling members. 
     These and other objects and advantages of the present invention will become clear to those skilled in the art in view of the description of the best presently known mode of carrying out the invention and the industrial applicability of the preferred embodiment as described herein and as illustrated in the several figures of the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The purposes and advantages of the present invention will be apparent from the following detailed description in conjunction with the appended drawings in which: 
         FIG. 1A  shows an overhead plan view of a production plant which embodies the system of fabrication of the present invention; 
         FIG. 1B  shows an detail of a portion of  FIG. 1A  which is enclosed in box labeled  1 B in  FIG. 1A ; 
         FIG. 2  illustrates a block unit as fabricated by the system of the present invention; 
         FIG. 3  shows an isometric view of a casting machine of the present invention in open configuration; 
         FIG. 4  shows an isometric view of a casting machine of the present invention in closed configuration; 
         FIG. 5  shows a detail view of a casting machine of the present invention in open configuration taken from detail  5  of  FIG. 3 ; 
         FIG. 6  shows a detail view of a casting machine of the present invention in open configuration taken from detail  6  of  FIG. 4 ; 
         FIG. 7  shows a cross-sectional view of the casting machine of the present invention in view  7  of  FIG. 3 , showing a first stage of the fabrication process; 
         FIGS. 8-19  show cross-sectional views of the casting machine of the present invention in sequential stages of the fabrication process following the first stage shown in  FIG. 7 ; 
         FIG. 20  shows an isometric view of the concrete delivery subsystem of the present invention including the hopper assembly with hopper carriage and hopper carriage mover of the present invention; 
         FIG. 21  shows an exploded isometric view of the concrete delivery subsystem of the present invention, including the hopper assembly with hopper carriage and hopper carriage mover of the present invention; 
         FIG. 22  shows an isometric view of the core lifter of the present invention; 
         FIGS. 23-24  are side plan views of the lateral to transverse conveyer subsystem of the present invention; and 
         FIGS. 25-30  are flow charts showing the stages in the fabrication of a structural member as manufactured by the system of the present invention. 
         FIG. 31  shows an overhead plan view of a production plant which embodies the system of fabrication of the second embodiment of the present invention; 
         FIG. 32  shows an detail of a portion of  FIG. 31  which is enclosed in box labeled A in  FIG. 31 ; 
         FIG. 33  shows an elevation view of a section of the production plant; 
         FIG. 34  shows a cross-sectional view of the casting machine of the present invention showing a first stage of the fabrication process; 
         FIGS. 35-42  show cross-sectional views of the casting machine of the present invention in sequential stages of the fabrication process following the first stage shown in  FIG. 34 ; 
         FIG. 43  shows a cross-sectional view of the concrete manifold of the present invention; 
         FIGS. 44-49  are flow charts showing the stages in the fabrication of a structural member as manufactured by the system of the present invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     A first embodiment of the present invention is a device, method and system for manufacture of precast concrete structural members. An overhead plan view of the preferred embodiment is the fabrication system illustrated in  FIGS. 1A  and B and the other figures of the drawings and is designated by the general reference character  10 . The system of the present invention  10  provides an automated system for the fabrication of precast modular blocks for building construction, which is highly efficient and allows the production of much greater numbers of precast modular blocks of a larger size then is possible by use of prior casting equipment and methods. 
     The purpose of the fabrication system  10  is to create precast block units of the type illustrated in  FIG. 2 . The typical precast block unit shown in perspective view in  FIG. 2  is designated by the reference number  1 . As shown, the block unit  1  is laterally symmetrical and includes a first sidewall  2  and a second sidewall  3 , situated on either side of an interior cavity  4 . A plurality of laterally spaced crossweb members  5  lie within the transverse interior cavity  4  and connect the first sidewall  2  to the second sidewall  3 . The block unit  1  is integrally formed (cast) and does not have any additional binding or connection components. 
     The blocks  1  are preferably at least partially hollow in order to easily incorporate structural reinforcement members such as rebar or steel lengths. The hollow construction of the block units  1  allows easy integration with other steel structural reinforcements, which may be included in floor and ceiling units. 
     Returning to  FIGS. 1A  and B,  FIG. 1A  shows the precast modular system  10  which includes a plan view of a production plant  12  largely surrounded by a perimeter wall  14 .  FIG. 1B  shows a detail view of the portion of  FIG. 1A  which is enclosed in the dotted box designated “ 1 B”. A concrete mixing subsystem  16  extends beyond a portion of the perimeter wall  14 . The plant  12  includes a rail system  18 , a block transport system  20 , a number of casting machines  22  and at least one curing oven  24 , of which two are shown in the figure. As will be discussed below, the concrete mixing subsystem  16  mixes concrete  26 , which is then deposited in a concrete hopper assembly  28 . The concrete hopper assembly  28  moves along the rail system  18 , until it aligns with one of the casting machines  22 . It delivers the concrete  26  into the casting machine  22 , which produces an initial set concrete block, which is rigid enough to stand on its own, but still requires curing. It is moved by conveyer belts  32  of the block transport system  20  to one of the curing ovens  24 , where it preferably remains at a temperature in the range of 140-180 degrees for 8 to 24 hours. It then emerges as an initial cure block  34 , where it is moved to a stocking area which may also serve as a final curing area  36  (not shown) where it preferably remains for an additional 28 days to complete its curing process, and is ready to ship as a completed block  1  (see  FIG. 2 ). The stocking area can be any conventional storage area, and as such, is not illustrated here. 
       FIG. 1B  shows a detail view of the portion of the overall plant  12  which is enclosed in the dashed box  1 B of  FIG. 1A . Referring now to both  FIGS. 1A and 1B , the concrete mixing subsystem  16  includes aggregate bins  38 . The aggregate bins  38  include a sand bin  40  and a gravel bin  42 . The concrete mixing subsystem  16  also includes a cement silo  44 , which is connected by a screw conveyer  46  to a cement hopper  48 . Two conveyer belts  50  deliver sand and gravel from the aggregate bins  38  to an aggregate hopper  52  which feeds into a concrete mixer  54 . The cement hopper  48  also feeds cement to the concrete mixer  54 . There is also a water line (not shown) connecting to the concrete mixer  54 . In operation, the conveyer belts  50  deliver sand and gravel from the aggregate bins  38  to the aggregate hopper  52 , which includes a scale (not shown) which weighs the incoming aggregate. When a predetermined amount is received, the conveyer belts  50  shut off, and the aggregate is poured into the concrete mixer  54 , along with cement from the cement silo  44  through the cement hopper  48 , and water. The concrete mixer  54  cycles until a mixed batch of concrete is ready. It is then poured down a chute  56  into the concrete hopper assembly  28 , which has been moved into position to receive it, although it is not shown in receiving position in this figure. A hopper wash-out area  58  is shown, which is preferably a 2-3 foot deep depression with a drain in the bottom. This hopper wash-out area  58  can be used to wash out the concrete hopper assembly  28  between concrete deliveries. 
     Referring now also to  FIGS. 7 and 21 , the rail system  18  includes lateral rails  60  and transverse rails  62 . The lateral rails  60  include casting machine rails  136 , which are included in the casting machines  22  and internal rails  164  included in the concrete hopper assembly  28 , as will be discussed below. The concrete hopper assembly  28  moves on the transverse rails  62  to be positioned over the hopper washout area  58 , which is under the concrete chute  56  in order to be washed out, and to receive mixed concrete  26 . It also moves along the transverse rails  62  to align with one of the multiple casting machines  22 , in order to load the casting machine  22  with concrete  26 . Thus a concrete delivery system  64  includes the rail system  18  and the concrete hopper assembly  28 , and moves the mixed concrete from the concrete mixing system  16  to fill the various casting machines  22  with concrete  26 . 
     The concrete hopper assembly  28  includes at least one concrete hopper  68 , a hopper carriage  70 , and hopper carriage mover  72 . These will be discussed in more detail below, but generally, the concrete hopper  68  contains the mixed concrete  26 , the hopper carriage mover  72  generally moves the concrete hopper  68  and hopper carriage  70  in a vertical direction, and the hopper carriage  70  then moves the concrete hopper  68  in a horizontal direction, in the reference plane of  FIGS. 1A  and B. 
     When the blocks  1  have achieved at least an initial set stage, where they are rigid enough to be self-supporting, they are ready to emerge from the casting machines  22  and are moved to be cured. The block transport system  20  moves these blocks and the block transport system  20  includes a number of conveying mechanisms, preferably conveyer belts  66 , both lateral and transverse in orientation (horizontal and vertically depicted in the FIGS.  1 A and B). 
     It will be understood by those skilled in the art, that other conveying mechanisms rather than belts may be used, such as rollers, ball bearings, etc. Thus the term “conveyer belts  66 ” shall be used in this document to include all of these possible conveying mechanisms and should not be construed as a limitation. 
     As illustrated in  FIGS. 1A  and B and the subsequent illustrations, it may be seen that the overall modular fabrication system  10  for precast block units  1  includes general components which recur modularly. Among those illustrated are a casting machine # 1   74 , a casting machine # 2   76  and so on for as many repetitions as are needed in the overall system. In the preferred embodiment  10  illustrated in  FIGS. 1A  and B, there are sixteen casting machines shown, with only the first two being provided with reference numbers. 
     The details of a representative one of the casting machines  22  is shown in  FIGS. 3-6 . The casting machine  22  is shown in perspective views in  FIGS. 3-4  in first open configuration  78  and then closed configuration  80 . Details of the perspective view of the left end of the casting machine  22  are shown in  FIGS. 5-6 . Additionally, the stages in the operating cycle of the casting machine are shown in a series of cross-sectional views taken initially from line  7 - 7  of  FIG. 3 , starting with  FIG. 7  and continuing through  FIG. 19 .  FIGS. 7-19 , which illustrate the stages of a cycle in the operation of the casting machine  22 , as well as  FIGS. 3-6  will be referred to generally in the following discussion, as well as specifically and individually below. 
     The casting machine  22  includes a frame  82 , mold sides  84 , mold end dams  86 , a bottom casting surface  88 , and a mold core subsystem  90 , which includes a top core  92 , a top core placement assembly  94 , a bottom core  96  and a bottom core extractor assembly  98 . The mold sides  84  are rotationally disposed on side pivots  100 , and are moved from the open angled position  78 , as in  FIG. 3 , to the closed upright position  80 , as in  FIG. 4 , by mold side hydraulics  102 . The mold end dams  86  are similarly rotationally disposed on end pivots  104 , and are moved from the closed upright position to the open angled position by mold end motors  106  (not visible). 
     When the casting machine  22  is in closed position  80 , as in  FIGS. 4 and 6 , the mold sides  84 , mold end dams  86 , and bottom casting surface  88  surround a cavity  108  into which the wet concrete will be poured. The top core  92  and bottom core  96  are placed into the cavity  108 , and serve to form upper and lower cavities in the block to be formed. As discussed above, the top core  92  and bottom core  96  have transverse channels  110  configured in them so that crossweb members are formed in the block to connect its two sides and provide it with structural strength. The mold sides  84 , mold end dams  86 , and bottom casting surface  88 , as well as the top core  92  and bottom core  96  together form a self-releasing mold  112 , which is the form into which the wet concrete will be poured to form the blocks. The mold is termed “self-releasing” as it is able to automatically pull away from the formed blocks without the laborious manual manipulation which is involved in prior art casting machines. 
     The top core placement assembly  94  is used to place the top core  92  into the cavity  108  before the concrete is poured, and then to extract it from the formed block once it has achieved its initial set. The top core placement assembly  94  includes core lifter hydraulics  114  and a core extractor  116 , which has a top core collar  118 , collar extractor hydraulics  120 , hydraulically moved horizontal retaining pin  122  and collar flange feet  124 . The top core placement assembly  94  is designed to engage an attachment bracket  130  on the top surface of the top core  92  which fits into the top core collar  118 . The top core collar  118  has a groove  132  into which the attachment bracket  130  fits. The attachment bracket  130  has a number of through holes (not visible) into which the retaining pins  122  pass, thus releasably locking the collar  118  onto the attachment bracket  130  of the top core  92 . The top core  92 , then can be grossly positioned by the retraction or extension of the core lifter hydraulics  114 , or moved more subtly by the collar extractor hydraulics  120 . Speaking generally, the core lifter hydraulics  114  are used for lifting the top core  92  and placing it into, or removing it from the cavity  108 , while the collar extractor hydraulics  120  are used for finer positioning or to carefully break the top core  92  free from the hardening cement block. 
     The bottom core  96  is attached to the bottom core extractor assembly  98  which also includes bottom casting surfaces  88 , which are rotatably attached by bottom surface pivots  126 . The bottom core extractor assembly  98  is raised and lowered by bottom core vertical hydraulics  128 . 
     The casting machine  22  also preferably has a block conveyor mechanism  134 , part of the block transport system  20 , (see  FIGS. 1A  and B) which may be rollers or one or more conveyer belts for removing the hardening cast blocks from the casting machine  22 . They may then be conveyed to a curing area for further hardening, as will be discussed below. 
     The casting machine  22  also preferably has a set of casting machine rails  136  for the delivery of the hopper carriage  70 , carrying the concrete hopper  68 , into the casting machine  22 . 
     The casting machine  22 , is thus configured with a mold core subsystem  90 , which fills the interior cavity  4  space of the block  1  which is to be cast (see  FIG. 2 ). The mold core subsystem  90  itself has transverse channels  110  (see  FIG. 5 ) which are filled with wet concrete to form the crossweb members  5 . It is to be understood that the blocks shown here are for purposes of illustration, and that the casting machine and mold core subsystem of the present invention may be modified in a number of ways to produce blocks of many different structures. The present invention is not to be limited to the production of only the illustrated type or structure of blocks, and many other variations will be obvious to those skilled in the art. For example the blocks may be of many varied lengths and widths, and the casting machines may be configured to produce such varied blocks. 
     As referred to above,  FIGS. 7-19  illustrate the stages of a cycle in the operation of the casting machine  22 , and these figures will be referred to generally in the following discussion. 
       FIG. 7  shows the initial stage in the fabrication cycle of a concrete block, as the casting machine  22  is ready to cast a block. The mold side hydraulics  102  have moved the mold sides  84  to upright position as they pivot on the side pivots  100 . Similarly, the mold end dams  86  have moved to closed position as they pivot on the end pivots  104  (see  FIGS. 5 and 6 ). The bottom surface panels  138  of the bottom casting surfaces  88  are rotated to horizontal position on the bottom surface pivots  126 . The bottom core extractor assembly  98  has been extended so that the bottom core  96  is positioned within the cavity  108 . The top core  92  has been placed in the cavity  108  as well by the core lifter subassembly  140  (see also  FIG. 22 ), which is part of the top core placement assembly  94 . The top core placement assembly  94  has been detached from the top core  92  and raised. The top core  92  and bottom core  96  are held in exact alignment by conical pins  142  that project from the top core  92  which are received by matching conical holes  144  in the bottom core  96 . At this point, all the casting surfaces have been cleaned and oiled, so that the cast concrete block eventually produced will be released more easily. 
       FIG. 8  shows the next stage of the casting cycle. The concrete mixing system  16  (see also  FIGS. 1A  and B and  FIG. 21 ) has prepared a batch of concrete  26 , and the concrete hopper  68  has moved to the concrete mixer  54  and received the concrete  26 . The hopper carriage  70  carrying the concrete hopper  68  then is moved by the hopper carriage mover  72  into alignment with the casting machine  22  and is driven onto the casting machine rails  136  to enter the casting machine  22 , and be positioned over the cavity  108  of the casting machine  22 . 
     The concrete hopper assembly  28  is shown and will be discussed in more detail below with regard to  FIGS. 20 and 21 . However, several features are visible in  FIG. 8 . These include generally the concrete hopper  68 , which is a long trough  146  having sloped sides  148  and a releasable bottom surface  138  preferably having two bottom panels  150  which are openable by hydraulic releasing mechanisms  152 . The trough  146  preferably has a triangular central divider  154  which will split the concrete delivery flow into two streams which will exit the hopper  68  through the two opened bottom panels  150  when it is appropriately positioned over the cavity  108  of the casting machine  22 . 
     The concrete hopper  68  is positioned on a hopper carriage  70  and is delivered to the casting machine  22  by a hopper carriage mover  72 , preferably by a system of rails, part of which is included in the casting machine  22  as the casting machine rails  136  discussed above. Pneumatic airbags  174  are positioned between portions of the hopper carriage  70  and the concrete hopper  68 , as will be discussed in detail below. At this stage, the airbags  174  are inflated so that the concrete hopper  68  is elevated slightly above the casting machine  22 . 
       FIG. 9  shows the next stage of the fabrication process. The pneumatic airbags  174  are deflated, so that the concrete hopper  68  lowers onto the self-releasing mold  112 , and engages the top core  92  to lock it rigidly into place. The concrete  26  is now ready to be poured into the cavity  108 . 
     Next,  FIG. 10  shows that two bottom panels  150  of the releasable bottom surface  138  have been opened by releasing mechanisms  152 . The triangular central divider  154  has split the concrete delivery flow into two streams which have now filled the cavity  108  with concrete  26 . 
     The empty concrete hopper  68  next is raised from the self-releasing mold  112 , by re-inflating the pneumatic airbags  174  as shown in  FIG. 11 , and then exits the casting machine  22 , as shown in  FIG. 12 . The concrete hopper  68  moves to the washout area (see  FIGS. 1A  and B) and is cleaned while the concrete  26  in the self-releasing mold  112  is vibrated to consolidate it. Vibration helps the concrete  26  to be distributed more evenly and to enter the transverse channels  110  (see  FIG. 5 ) formed in the top and bottom cores which will form the crossweb members  5  pieces of the finished block  1  (see  FIG. 2 ). 
     In the next stage of fabrication, a screed device (not shown) finishes the top surface of the concrete, and the machine idles until temperature sensors (not shown) signal that the initial concrete set is completed. 
     When the initial set is complete, the top core placement assembly  94  is lowered by the core lifter hydraulics  114 , as shown in  FIG. 13 . The slot  132  in the top core collar  118  engages the attachment bracket  130  of the top core  92 , and the retaining pin  122  engages the through holes  156  of the attachment bracket  130 . 
       FIG. 14  shows that next the collar extractor hydraulics  120  retract slightly, causing the initial set concrete block  30  to break away from the top core  92 , as it is lifted by the attachment bracket  130  and top core collar  118 . The flange feet  124  of the top core extractor assembly  116  contact the top surface of the now solid initial set concrete block  30 , and prevent it from lifting as the collar extractor hydraulics  120  lift the top core collar  118  with the attached top core  92 . The top core  92  is thus pulled gently away from the initial set concrete block  30 , which is held down by the flange feet  124 . The movement of the collar extractor hydraulics  120  is finely controlled, and releases the top core  92  from the initial set concrete block  30  without tearing the concrete. Although too fine to be shown well in the figures, the profile of the top core  92  has a slight taper preferably of approximately one degree so that the top portion is slightly wider than the bottom, thus aiding in the self-releasing process. 
     In  FIG. 15 , it is shown that once the top core  92  has been broken free of the initial set concrete block  30 , and is in no danger of tearing the concrete, the core lifter hydraulics  114  are activated to lift the top core  92  out of the cavity  108 . 
     In  FIG. 16 , the end dams  86  (see  FIGS. 5-6 ) have been pivoted open, and the mold side hydraulics  102  have moved the mold sides  84  to recline, as they pivot on the side pivots  100 . The sides of the initial set concrete block  30  are now free. 
     In  FIG. 17 , bottom surface panels  138  of the bottom casting surfaces  88  have been rotated to vertical, and the bottom core  96 , with the initial set concrete block  30 , has been lowered by the bottom core vertical hydraulics  128  until the initial set block  30  contacts the block conveyer mechanism  134 . 
       FIG. 18  shows that the bottom core  96  has been retracted even further, until the initial set concrete block  30  has broken free from the bottom core  96  and is entirely supported by the block conveyer mechanism  134 . The bottom core vertical hydraulics  128  continue to retract until the bottom core  96  is detached from the initial set concrete block  30 , and the initial set concrete block  30  stands free of the casting machine self-releasing mold  112  on the block conveyer mechanism  134 . Although too fine to be shown well in the figures, the profile of the bottom core  96  also has a slight taper preferably of approximately one degree so that the bottom portion is slightly wider than the top, thus also aiding in the self-releasing process. 
     In  FIG. 19 , the block conveyer mechanism  134  has moved the initial set concrete block  30  (not shown) out of the casting machine  22 . The initial set concrete block  30  then enters the initial set heated curing oven  24  (see  FIGS. 1A  and B), where it hardens further. The casting machine  22  is automatically cleaned with high pressure water spray (not shown) and the surfaces of the casting machine  22  are oiled with release agent spray (not shown). The cycle is ready to start again, and next returns to the stage illustrated in  FIG. 7 . 
     From the description of the cycle above, it can be more easily understood what is meant by the term “self-releasing mold”, as the movement of the sides, bottom surface, end dams and cores of the mold is completely automated, and requires no human manipulation to remove the solidified block from the casting machine, or for that matter from the entire system. After the block is transported from the casting machine, it is conveyed to curing areas for final hardening, and then further conveyed to a transport area, again all by the automated equipment of the system. Ideally, the system can operate by adding concrete to the input, and receiving finished precast blocks from the output with little or no human manipulation. The plant is meant to be staffed only with inspectors and mechanics who watch the entire process and intervene only for routine maintenance or to halt production when something breaks or malfunctions. This obviously provides great advantages over the prior casting systems which require a great deal of human labor and participation. 
     Referring again to  FIGS. 1A  and B,  7  and  20 - 21 , the operation of the casting machines  22  is preferably staggered, so that, for instance, casting machine # 1   74  is first placed in closed position, in order to receive concrete mix. The concrete hopper  68 , mounted on hopper carriage  70  and hopper carriage mover  72  has been conveyed along transverse rails  62  of the rail system  18  first to the mixed concrete source  16 , where it is loaded with mixed concrete, and then is moved along the transverse rails  62  of the rail system  18  as shown in  FIG. 1A  in a vertical direction, until it is positioned by the hopper carriage mover  72  to enter casting machine # 1   74 . It then is moved on internal rails  164 , (see  FIG. 21 ) of the hopper carriage mover  72 , in a direction seen as horizontal in  FIGS. 1A  and B, until it is fully positioned on the casting machine rails  136 , in casting machine # 1   74 , and delivers the load of concrete into the closed mold of casting machine # 1   74 . When this operation is completed, the hopper carriage mover  72  withdraws the concrete hopper  68  from casting machine # 1   74 , and returns along the transverse rails  62  of the concrete delivery subsystem  64  to the concrete mixing system  16  for another load of concrete. It then moves to casting machine # 2   76 , now in closed position, where it delivers the load of concrete. This pattern continues until all casting machines  22  have been filled in a “complete loading cycle”. For the purposes of this patent application, the term “complete loading cycle” will be used to mean the amount of time necessary for the concrete hopper assembly  28  to load all casting machines # 1  . . . N, and the solidified block  30  from casting machine # 1   74  has completed its initial set stage, and has been removed, so that casting machine # 1   74  is ready to receive the next load of concrete. 
     It is to be understood that the system of sixteen casting machines shown is not to be construed as a limitation. In the preferred embodiment  10 , the number of casting machines is chosen so that the initial set time of the concrete coincides with the timing of a complete loading cycle, so that the concrete hopper assembly  28  is in continuous operation. It is also true that the design does not depend on any particular sequence of concrete delivery as described above, or even on all casting machines being in operation. The operation of individual casting machines is mutually independent. 
     After the block  30  has achieved its initial set stage, and is solid enough to be removed from the casting machine  22 , the block  30  is then moved to the initial set heated curing ovens  24 , by the block transport system  20 , which is preferably a series of automated conveyer belts  66 . The temperature of the initial set heated curing ovens  24  is also carefully regulated so that the curing time corresponds to the overall cycle time, and doesn&#39;t create a “bottleneck” in the production flow. Typically, this temperature is in the range of 140-180 degrees F. for 8 to 24 hours. The initial cure block  34  is then moved to the final curing area  36  where the final curing stage takes place for typically 28 days before the completed block  1  is moved to a transport area (not shown) for shipping. The length of the conveyer belts  66  of the block transport system  20  is preferably chosen so that a number of blocks  30  can be held without interfering with the timing of the complete loading cycle, referred to above. 
     An important part of the overall system, which allows for automated operation, is the concrete delivery system  64 , portions of which have been partially described above. For purposes of this discussion, the concrete delivery system  64  will include the concrete hopper assembly  28  and the rail system  18  upon which it rides (see  FIG. 1 ). The concrete hopper assembly  28  is shown in an isometric view in  FIG. 20  and an exploded isometric view in  FIG. 21 . The concrete hopper assembly  28  generally includes the concrete hopper  68 , the hopper carriage  70  and the hopper carriage mover  72 . 
     As discussed above with reference to  FIG. 8 , and with continued reference to  FIGS. 20-21 , the concrete hopper  68  includes a long trough  146  having sloped sides  148  and a releasable bottom surface  138  preferably having two bottom panels  150  which are openable by releasing mechanisms  152 . The trough  146  preferably has a triangular central divider  154  which will split the concrete delivery flow into two streams which will exit the hopper  68  through the two opened bottom panels  150  when it is appropriately positioned over the cavity  108  of the casting machine  22 . 
     The concrete hopper  68  rides on the hopper carriage  70  which is formed from carriage frame members  160  fitted with a number of wheel clusters  162 . At least one set of wheel clusters  162  is fitted with a set of motor boxes  172 , which will drive that set of the wheel clusters  162 . 
     The hopper carriage mover  72  includes a set of internal rails  164  which are attached to primary beams  166 . The primary beams  166  are attached to transverse beams  168 , which are also preferably attached to transverse wheel clusters  170 , and are powered by motor boxes  172 . 
     Referring now also to  FIGS. 1A  and B, the hopper carriage mover  72  uses the motor boxes  172  to drive the transverse wheel clusters  170  upon the pair of transverse rails  62  to move the whole concrete hopper assembly  28  to the concrete mixing system  16  for filling, and then to align with any of the multiple casting machines  22 . 
     The casting machines include a set of casting machine rails  136  (see also  FIG. 7 ), and the hopper carriage mover  72  moves until its set of internal rails  164  are aligned with these casting machine rails  136 . The hopper carriage mover  72  then stops, and the motor boxes  172  of the hopper carriage  70  then drive the wheel clusters  162  to move upon the internal rails  164  of the hopper carriage mover  72  and to carry the concrete hopper  68  into position above the cavity  108  of the casting machine  22 . Pneumatic airbags  174  on the frame  176  of the wheel clusters  172  are inflated when the concrete hopper  68  is being moved above the casting machine (see also  FIG. 8 ), and are deflated to lower the concrete hopper  68  onto the casting machine  22  (see  FIG. 9 ). The concrete  26  is released into the cavity  108  of the casting machine  22 , as described above. The airbags  174  then re-inflate to raise the concrete hopper  68 , and the hopper carriage  70  drives from the casting machine rails  136  onto the internal rails  164  of the hopper carriage mover  72  again. The hopper carriage mover  72  then drives on the transverse rails  62  back to the concrete mixing system  16 , is filled, and proceeds to the next casting machine  76 . This cycle repeats until all casting machines  22  have been filled, at which time, the first casting machine  74  to be filled is preferably through with its casting cycle, has ejected its initial set concrete block  30  and is ready to be filled again. 
     Thus to describe the general operation of the concrete delivery subsystem  64  in simple terms, in reference to the orientation of  FIGS. 1A  and B, the hopper carriage mover  72  generally moves the concrete hopper  68  and hopper carriage  70  in a vertical direction, and the hopper carriage  70  then moves the concrete hopper  68  horizontally. 
       FIG. 22  shows an isometric view of the core lifter subassembly  140 , of which a cross-sectional view  7 - 7  is included as part of  FIG. 7 , which is referred to now also. The core lifter subassembly  140  includes the housing  158 , collar flange feet  124 , top core collar  118  having slot  132 , retaining pins  122 , and extractor hydraulics  114 . The core lifter subassembly  140  is included as part of the top core extractor assembly  116 , and this assembly is also involved in the placement of the top core  92 , and thus is also properly referred to as part of the top core placement assembly  94 . As described above, the core lifter subassembly  140  is raised and lowered by core lifter hydraulics  114 . When lowered, slot  132  engages the attachment bracket  130  of the top core  92  and retaining pins  122  engage through holes (not visible) on the top core attachment bracket  130 . The top core  92  can thus be lifted by retraction of the top core lifter hydraulics  114 . Also as described above, the collar extractor hydraulics  120  are used to pull the top core  92  from the initial set concrete block as part of the self-releasing operation of the casting machine  22 . 
     Another aspect of the system  10 , which allows the automated routing of the initial set blocks  30 , is the lateral to transverse conveyer subsystem  178 , which can be seen in the right-hand portion of  FIG. 1A , and in  FIGS. 23 and 24 . For purposes of this discussion and referring to the orientation of  FIG. 1A , the left-to-right movement of the blocks will be referred to as “lateral” and movement from top of the page to bottom, or vice-versa, will be referred to as “transverse”. The initial cure blocks  30  emerge from the casting machines  22  along the conveyer belts  66  in a direction which is laterally to the right in  FIG. 1A . Although it is not a requirement, for design considerations of the production plant  12 , it may be desired that the curing ovens  24  be located transversely from the lateral conveyer belts  66  emerging from the casting machines  22 . Thus the blocks  30  must be made to travel at right angles to their initial lateral direction to reach the curing ovens  24 . To accomplish this, a number of transverse conveyers  180  are provided which are interspersed with the lateral conveyers  66 , which in the area of the lateral to transverse conveyer subsystem  178 , are reduced in length, and will be referred to as reduced lateral conveyers  182 . Obviously, if both the transverse conveyers  180  and reduced lateral conveyers  182 , each running at right angles to each other, were to contact the initial set blocks  30  at the same time, the blocks would spin or tip over, causing a pile-up of blocks. Therefore, the lateral to transverse conveyer subsystem  178  is designed so that the blocks  30  are moved by either the transverse conveyers  180  or reduced lateral conveyers  182 , but not both at the same time. 
     This is accomplished by the system illustrated in more detail in  FIGS. 23 and 24 , which are side views of an initial set block  30  being moved by the lateral to transverse conveyer subsystem  178  from a lateral direction in  FIG. 23  to a transverse direction in  FIG. 24 . In  FIG. 23  the block  30  is supported by a number of reduced lateral conveyers  182 . Interspersed with the reduced lateral conveyers  182  are the transverse conveyers  180 . The reduced lateral conveyers  182  include pneumatic air bags  184 , which are similar to the pneumatic air bags included in the concrete hopper assembly  28  discussed above. These pneumatic air bags  184  are currently inflated in  FIG. 23 , so that the conveying surfaces of reduced lateral conveyers  182  are higher than those of the transverse conveyers  180 . The block  30  thus only contacts the reduced lateral conveyers  182  and is moved only in a lateral direction. 
       FIG. 24  shows the effect of deflating the pneumatic air bags  184 , so that now the block  30  rests on the transverse conveyers  180 . The block  30  can now be moved in a transverse direction into the curing ovens  24  (see  FIG. 1A ). 
     It should be understood that number and placement of the transverse conveyers  180  and the reduced lateral conveyers  182  is not limited to those shown in  FIG. 1A . In fact, the transverse conveyers  180  are shown more closely spaced near the top right corner of  FIG. 1A  than near the bottom of this figure. The closer spacing allows blocks of shorter lengths to be manipulated, while the wider spacing may be sufficient for longer blocks. It should also be understood that a lateral to transverse conveyer subsystem may not be required at all in the instance of a plant which has enough continuous length that the curing ovens may be fed by the lateral conveyers directly, without the necessity of making a turn in the production flow. However, the option of using a lateral to transverse conveyer subsystem allows more flexibility in the selection of plant sites and production design. 
     The production cycle using the modular precasting system of the present invention is summarized with reference to flowcharts seen in  FIGS. 25-30 . Referring to  FIG. 25 , the basic major stages of the manufacturing process are shown. These include Begin Cycle: Ready to Cast  200 , Preparing Concrete  300 , Placing Concrete  400 , Waiting for Initial Set  500 , and Removing Block from Casting Machine  600 . The cycle is then repeated to produce the next block. 
     As seen in  FIG. 26 , the stages within the first major stage, Begin Cycle: Ready to Cast  200 , are: 
     Mold sides are closed  202 ; 
     End dams are closed  204 ; 
     Bottom casting surfaces hinges are raised to horizontal  206 ; 
     Top and bottom cores are inserted  208 ; 
     Core lifter is detached from top core and raised  210 ; and 
     All casting surfaces are clean and oiled  212 . 
     As seen in  FIG. 27 , the stages within the second major stage, Preparing Concrete  300 , are: 
     Concrete mixer prepares a batch  302 ; 
     Concrete hopper moves to concrete mixer  304 ; 
     Concrete is poured from mixer to hopper  306 ; 
     Hopper moves to rear of casting machine  308 ; 
     Hopper enters casting machine  310 ; and 
     Hopper lowers onto mold  312 . 
     The stages within the third major stage, Placing Concrete  400 , as seen in  FIG. 28  are: 
     Hopper guillotine blades open and concrete enters mold  402 ; 
     Hopper is raised from mold  404 ; 
     Hopper exits casting machine  406 ; and 
     Hopper moves to washout area and is cleaned, while concrete is consolidated (vibrated)  408 . 
     As seen in  FIG. 29 , the stages within the fourth major stage, Waiting for Initial Set  500 , are: 
     Screed device finishes concrete top surface  502 ; and 
     Machine idles until temperature sensors signal initial concrete set  504 . 
     As seen in  FIG. 30 , the stages within the fifth major stage, Removing Block from Casting Machine  600  are: 
     Core lifter is lowered and engages top core with horizontal hydraulic pins  602 ; 
     Core lifter short vertical hydraulics retract and pull top core free from concrete block  604 ; 
     Frame long vertical hydraulics retract and lift core lifter and top core  606 ; 
     End dams hinge open  608 ; 
     Mold sides open  610 ; 
     Bottom casting surfaces are hinged down to vertical  612 ; 
     Bottom core and block are lowered until block contacts conveyor belt  614 ; 
     Bottom core continues downward, pulling free from block, which is now freestanding on conveyor belt  616 ; 
     Block exits front of machine and enters initial set heated curing area  618 ; 
     Casting machine is cleaned with high pressure water spray  620 ; 
     Casting surfaces are oiled with release agent  622 ; 
     Casting machine is “closed”: 
     Mold sides are closed, 
     End dams are closed, 
     Bottom casting surfaces hinges are raised, 
     Top and bottom cores are inserted, 
     Core lifter is detached from top core and raised  624 . 
     While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above described exemplary embodiments, but should be defined only in accordance with the appended claims and their equivalents. 
     A second embodiment which is presently most preferred is a device, method and system for manufacture of precast concrete structural members which includes many new features. The original element numbering has been retained where the original elements are substantially unchanged. Where existing elements have been modified, but perform substantially the same function, the element number has had  700  added to the original number, so that for example “block transport system  20 ” is now “block transport system  720 ”. Where new elements are included which were not present in the original embodiment, the element numbers are all numbered starting with “ 900 ”. Drawings for the new embodiment are added to the original drawings starting at new  FIG. 31 . An overhead plan view of the second preferred embodiment is the fabrication system illustrated in  FIGS. 31-32  and is designated by the general reference character  710 . The system of the present invention  710  provides an automated system for the fabrication of precast modular blocks for building construction, which is highly efficient and allows the production of much greater numbers of precast modular blocks of a larger size then is possible by use of prior casting equipment and methods. 
     The purpose of the fabrication system  710  is to create precast block units of the type illustrated in  FIG. 2 . The typical precast block unit shown in perspective view in  FIG. 2  is designated by the reference number  1 . As shown, the block unit  1  is laterally symmetrical and includes a first sidewall  2  and a second sidewall  3 , situated on either side of an interior cavity  4 . A plurality of laterally spaced crossweb members  5  lie within the transverse interior cavity  4  and connect the first sidewall  2  to the second sidewall  3 . The block unit  1  is integrally formed (cast) and does not have any additional binding or connection components. 
     The blocks  1  are preferably at least partially hollow in order to easily incorporate structural reinforcement members such as rebar or steel lengths. The hollow construction of the block units  1  allows easy integration with other steel structural reinforcements, which may be included in floor and ceiling units. 
     Returning to  FIGS. 31-33 ,  FIG. 31  shows the precast modular system  710  which includes a plan view of a production plant  712  largely surrounded by a perimeter wall  14 .  FIG. 32  shows a detail view of the portion of  FIG. 31  which is enclosed in the dotted box designated “A”. A concrete mixing subsystem  716  extends beyond a portion of the perimeter wall  14 . The plant  712  includes a block transport system  720 , a number of casting machines  722  and at least one curing oven  724 , of which one is shown in the figure. As will be discussed below, the concrete mixing subsystem  716  mixes concrete  26 , which is then pumped to one or more concrete placement booms  901 . The placement boom delivers the concrete via a delivery hose  902  to a detachable manifold  903 , which splits the concrete into two streams which flow into the casting machine  722 . This produces an initial set concrete block  30 , which is rigid enough to stand on its own, but still requires curing. It is moved by conveyer belts  32  of the block transport system  720  to one of the curing ovens  724 , where it preferably remains at a temperature in the range of 140-180 degrees for 8 to 24 hours. It then emerges as an initial cure block  34 , where it is moved to a stocking area which may also serve as a final curing area  36  (not shown) where it preferably remains for an additional 28 days to complete its curing process, and is ready to ship as a completed block  1  (see  FIG. 2 ). The stocking area can be any conventional storage area, and as such, is not illustrated here. 
       FIG. 32  shows a detail view of the portion of the overall plant  712  which is enclosed in the dashed box “A” of  FIG. 31 . Referring now to  FIGS. 31-33 , the concrete mixing subsystem  716  includes aggregate bins  38 . The aggregate bins  38  include one or more sand bins  40  and one or more gravel bins  42 . The concrete mixing subsystem  716  also includes one or more cement silos  44 , which are connected by a screw conveyer  46  to a cement hopper  48 . Conveyor belts  50  deliver sand and gravel from the aggregate bins  38  to an aggregate hopper  52  which feeds into a concrete mixer  54 . The cement hopper  48  also feeds cement to the concrete mixer  54 . There is also a water line (not shown) connecting to the concrete mixer  54 . In operation, the conveyer belts  50  deliver sand and gravel from the aggregate bins  38  to the aggregate hopper  52 , which includes a scale (not shown) which weighs the incoming aggregate. When a predetermined amount is received, the conveyer belts  50  shut off, and the aggregate is poured into the concrete mixer  54 , along with cement from the cement silo  44  through the cement hopper  48 , and water. The concrete mixer  54  cycles until a mixed batch of concrete is ready. It is then poured down a chute  56  into the concrete pump  900 . The concrete pump moves the concrete to one or more concrete placement booms  901  (see  FIG. 33 ), which deliver the concrete via a flexible concrete delivery hose  902  and a concrete manifold  903  to the casting machines  722 . Thus a concrete delivery system  764  includes the concrete pump  900 , the concrete placement booms  901 , the flexible concrete delivery hose  902  and the concrete manifold  903  and moves the mixed concrete from the concrete mixing system  716  to fill the various casting machines  722  with concrete  26 . 
     When the blocks  1  have achieved at least an initial set stage, where they are rigid enough to be self-supporting, they are ready to emerge from the casting machines  722  and are moved to be cured. The block transport system  720  moves these blocks and the block transport system  720  includes a number of conveying mechanisms, preferably conveyer belts  66  and an overhead crane  906 . 
     It will be understood by those skilled in the art, that other conveying mechanisms rather than belts may be used, such as rollers, ball bearings, etc. Thus the term “conveyer belts  66 ” shall be used in this document to include all of these possible conveying mechanisms and should not be construed as a limitation. 
     As illustrated in  FIGS. 31 and 32  and the subsequent illustrations, it may be seen that the overall modular fabrication system  710  for precast block units  1  includes general components which recur modularly. Among those illustrated are a casting machine # 1   774 , a casting machine # 2   776  and so on for as many repetitions as are needed in the overall system. In the preferred embodiment  710  illustrated in  FIGS. 31 and 32 , there are fifty casting machines shown, with only the first two being provided with reference numbers. 
     The details of a representative one of the casting machines  722  is shown in  FIGS. 34-42 . The stages in the operating cycle of the casting machine are shown in a series of cross-sectional views starting with  FIG. 34  and continuing through  FIG. 42 .  FIGS. 34-42 , which illustrate the stages of a cycle in the operation of the casting machine  722 , will be referred to generally in the following discussion, as well as specifically and individually below. 
     The casting machine  722  includes a frame  82 , mold sides with integrally formed end dams  784 , a bottom casting surface  788 , and a mold core subsystem  90 , which includes a top core  92 , and a bottom core  96 . The mold sides with integral end dams  784  are rotationally disposed on side pivots  100 , and are moved from the open angled position  78 , as in  FIG. 39 , to the closed upright position  80 , as in  FIG. 34 , by mold side hydraulics  102 . One mold side holds a removable form liner  905 , which can have any pattern carved into its surface facing the cavity  108 . This pattern will be left in relief on the outer surface of the concrete block. This allows the blocks to display architectural features such as bevels, split-face, corporate logos, and more. When the casting machine  722  is in closed position  80 , as in  FIG. 34 , the mold sides  784  and bottom casting surface  788  surround a cavity  108  into which the wet concrete will be pumped. The top core  92  and bottom core  96  are placed into the cavity  108 , and serve to form upper and lower cavities in the block to be formed. As discussed above, the top core  92  and bottom core  96  have transverse channels  110  configured in them so that crossweb members are formed in the block to connect its two sides and provide it with structural strength. The mold sides  784  and bottom casting surface  788 , as well as the top core  92  and bottom core  96  together form a self-releasing mold  812 , which is the form into which the wet concrete will be poured to form the blocks. The mold is termed “self-releasing” as it is able to automatically pull away from the formed blocks without the laborious manual manipulation which is involved in prior art casting machines. 
     The core lifter hydraulics  114  are used for lifting the top core  92  and placing it into, or removing it from the cavity  108 . 
     The bottom core  96  is raised and lowered by bottom core vertical hydraulics  128 . 
     The casting machine  722  also preferably interfaces with a block conveyor mechanism  134 , part of the block transport system  720 , (see  FIGS. 31 and 32 ) which may be rollers or one or more conveyer belts for removing the hardening cast blocks from the casting machine  722 . They may then be conveyed to a curing area for further hardening, as will be discussed below. 
     The casting machine  722 , is thus configured with a mold core subsystem  790 , which fills the interior cavity  4  space of the block  1  which is to be cast (see  FIG. 2 ). The mold core subsystem  790  itself has transverse channels  110  (see  FIG. 5 ) which are filled with wet concrete to form the crossweb members  5 . It is to be understood that the blocks shown here are for purposes of illustration, and that the casting machine and mold core subsystem of the present invention may be modified in a number of ways to produce blocks of many different structures. The present invention is not to be limited to the production of only the illustrated type or structure of blocks, and many other variations will be obvious to those skilled in the art. For example the blocks may be of many varied lengths and widths, and the casting machines may be configured to produce such varied blocks. 
     As referred to above,  FIGS. 34-42  illustrate the stages of a cycle in the operation of the casting machine  722 , and these figures will be referred to generally in the following discussion. 
       FIG. 34  shows the initial stage in the fabrication cycle of a concrete block, as the casting machine  722  is ready to cast a block. The mold side hydraulics  102  have moved the mold sides  784  to upright position as they pivot on the side pivots  100 . The bottom surface panels  838  of the bottom casting surfaces  788  are rotated to horizontal position on the bottom surface pivots  826 . The bottom core vertical hydraulics  128  have been extended so that the bottom core  96  is positioned within the cavity  108 . The top core  92  has been placed in the cavity  108  as well by the top core vertical hydraulics  114 . The top core  92  and bottom core  96  are held in exact alignment by conical pins  142  that project from the top core  92  which are received by matching conical holes  144  in the bottom core  96 . At this point, all the casting surfaces have been cleaned and oiled, so that the cast concrete block eventually produced will be released more easily. 
       FIG. 35  shows the next stage of the casting cycle. The concrete mixing system  716  (see also  FIGS. 31-33 ) has prepared a batch of concrete  26  and transferred it to the concrete pump  900 . The concrete placement boom  901 , attached to the flexible concrete delivery hose  902 , which is attached to the concrete manifold  903 , have all moved to the casting machine  722 . The concrete port valves  904  have been opened and the concrete manifold  903  has been clamped over the concrete ports  907 . 
     As seen in  FIG. 36 , the concrete  26  is pumped through the manifold  903 , which splits the delivery flow into two streams which enter through the concrete ports  907  and fill the cavity  108  (see  FIG. 34 ).  FIG. 43  shows a cross-sectional view of the manifold, including the manifold splitting edge  909 . The splitting edge as shown has an angle of α 910 which is preferably in the range of 25 degrees to 45 degrees and most preferably 30 degrees. It is important that the splitting edge  909  be sharp rather than rounded or flat, to prevent the concrete from jamming in the manifold  903 . The splitting edge  909  has a fillet radius preferably in the range of 0.005″-0.01″. In practice, it is difficult to keep a finer edge from “feathering” under the impact of wet flowing concrete, and a larger fillet radius allows the concrete sand and aggregate to “catch” on the edge and propagate a jam. 
     In  FIG. 37 , the concrete manifold  903 , delivery hose  902 , (see  FIG. 33 ) and placement boom  901  move on to the next casting machine to be filled with concrete, and the concrete port valves  904  are closed. The concrete  26  in the self-releasing mold  812  is vibrated to consolidate it. Vibration helps the concrete  26  to be distributed more evenly and to enter the transverse channels  110  formed in the top and bottom cores which will form the crossweb members  5  pieces of the finished block  1  (see  FIG. 2 ). 
     In the next stage of fabrication, the machine idles until temperature sensors (not shown) signal that the initial concrete set is completed. 
     Referring to  FIG. 38 , when the initial set is complete, the top core vertical hydraulics  114  pull the top core  92  free of the initial set concrete block  30 . Although too fine to be shown well in the figures, the profile of the top core  92  has a slight taper preferably of approximately one degree so that the top portion is slightly wider than the bottom, thus aiding in the self-releasing process. 
     In  FIG. 39 , the mold side hydraulics  102  have moved the mold sides  784  to recline, as they pivot on the side pivots  100 . The sides of the initial set concrete block  30  are now free. The bottom surface panels  838  of the bottom casting surfaces  788  have been rotated to vertical. 
     In  FIG. 40 , the bottom core  96 , with the initial set concrete block  30 , has been lowered by the bottom core vertical hydraulics  128  until the initial set block  30  contacts the block conveyer mechanism  134 . 
       FIG. 41  shows that the bottom core  96  has been retracted even further, until the initial set concrete block  30  has broken free from the bottom core  96  and is entirely supported by the block conveyer mechanism  134 . The bottom core vertical hydraulics  128  continue to retract until the bottom core  96  is detached from the initial set concrete block  30 , and the initial set concrete block  30  stands free of the casting machine self-releasing mold  812  on the block conveyer mechanism  134 . Although too fine to be shown well in the figures, the profile of the bottom core  96  also has a slight taper preferably of approximately one degree so that the bottom portion is slightly wider than the top, thus also aiding in the self-releasing process. 
     In  FIG. 42 , the block conveyer mechanism  134  has moved the initial set concrete block  30  (not shown) out of the casting machine  722 . The initial set concrete block  30  then enters the initial set heated curing oven  724  (see  FIGS. 31 and 32 ), where it hardens further. The casting machine  722  is automatically cleaned with high pressure water spray or high pressure air (not shown) and the surfaces of the casting machine  722  are oiled with release agent spray (not shown). The cycle is ready to start again, and next returns to the stage illustrated in  FIG. 34 . 
     From the description of the cycle above, it can be more easily understood what is meant by the term “self-releasing mold”, as the movement of the sides with integrally formed end dams, bottom surface, and cores of the mold is completely automated, and requires no human manipulation to remove the solidified block from the casting machine, or for that matter from the entire system. After the block is transported from the casting machine, it is conveyed to curing areas for final hardening, and then further conveyed to a transport area, again all by the automated equipment of the system. Ideally, the system can operate by adding concrete to the input, and receiving finished precast blocks from the output with little or no human manipulation. The plant is meant to be staffed only with inspectors and mechanics who watch the entire process and intervene only for routine maintenance or to halt production when something breaks or malfunctions. This obviously provides great advantages over the prior casting systems which require a great deal of human labor and participation. 
     Referring again to  FIGS. 31-33 , the operation of the casting machines  722  is preferably staggered, so that, for instance, casting machine # 1   774  is first placed in closed position, in order to receive concrete mix. The concrete placement boom  901  with attached delivery hose  902  and manifold  903  are moved to casting machine # 1   774  and fill the closed mold of casting machine # 1  with concrete. The concrete placement boom  901  with attached delivery hose  902  and manifold  903  are then moved to casting machine # 2   776  and fill the closed mold of casting machine # 2  with concrete. This pattern continues until all casting machines  722  have been filled in a “complete loading cycle”. For the purposes of this patent application, the term “complete loading cycle” will be used to mean the amount of time necessary to load all casting machines # 1  . . . N, and the solidified block  30  from casting machine # 1   774  has completed its initial set stage, and has been removed, so that casting machine # 1   774  is ready to receive the next load of concrete. 
     It is to be understood that the system of fifty casting machines shown is not to be construed as a limitation. In the preferred embodiment  710 , the number of casting machines is chosen so that the initial set time of the concrete coincides with the timing of a complete loading cycle, so that the concrete placement boom  901  is in continuous operation. It is also true that the design does not depend on any particular sequence of concrete delivery as described above, or even on all casting machines being in operation. The operation of individual casting machines is mutually independent. 
     After the block  30  has achieved its initial set stage, and is solid enough to be removed from the casting machine  722 , the block  30  is then moved to the initial set heated curing ovens  724 , by the block transport system  720 , which is preferably a series of automated conveyer belts  66 . The temperature of the initial set heated curing ovens  24  is also carefully regulated so that the curing time corresponds to the overall cycle time, and doesn&#39;t create a “bottleneck” in the production flow. Typically, this temperature is in the range of 140-180 degrees F. for 8 to 24 hours. The initial cure block  34  is then moved to the final curing area  36  where the final curing stage takes place for typically 28 days before the completed block  1  is moved to a transport area (not shown) for shipping. The length of the conveyer belts  66  of the block transport system  720  is preferably chosen so that a number of blocks  30  can be held without interfering with the timing of the complete loading cycle, referred to above. 
     Again referring to  FIG. 31-33 , an important part of the overall system, which allows for automated operation, is the concrete delivery system  764 , portions of which have been partially described above. For purposes of this discussion, the concrete delivery system  764  will include the concrete pump  900  and one or more concrete placement booms  901 , each with an attached concrete delivery hose  902  and concrete manifold  903 . 
     Another aspect of the system  10 , which allows the automated routing of the initial set blocks  30 , is the block transport system  720 . For purposes of this discussion and referring to the orientation of  FIG. 31 , the left-to-right movement of the blocks will be referred to as “lateral” and movement from top of the page to bottom, or vice-versa, will be referred to as “transverse”. The initial cure blocks  30  emerge from the casting machines  722  along the conveyer belts  66  in a direction which is laterally to the right or left in  FIG. 31 . Although it is not a requirement, for design considerations of the production plant  712 , it may be desired that the curing ovens  724  be located transversely from the lateral conveyer belts  66  emerging from the casting machines  722 . Thus the blocks  30  must be made to travel at right angles to their initial lateral direction to reach the curing ovens  24 . To accomplish this, an overhead crane  906  with lifting attachments  908  (see  FIG. 33 ) can move transversely over all fifty conveyors  66 , picking up blocks  30  and moving them to the curing ovens  724 . It should be understood that a lateral to transverse conveyer subsystem may not be required at all in the instance of a plant which has enough continuous length that the curing ovens may be fed by the lateral conveyers directly, without the necessity of making a turn in the production flow. However, the option of using a lateral to transverse conveyer subsystem allows more flexibility in the selection of plant sites and production design. 
     The production cycle using the modular precasting system of the present invention is summarized with reference to flowcharts seen in  FIGS. 44-49 . Referring to  FIG. 44 , the basic major stages of the manufacturing process are shown. These include Begin Cycle: Ready to Cast  1200 , Preparing Concrete  1300 , Placing Concrete  1400 , Waiting for Initial Set  1500 , and Removing Block from Casting Machine  1600 . The cycle is then repeated to produce the next block. 
     As seen in  FIG. 45 , the stages within the first major stage, Begin Cycle: Ready to Cast  1200 , are: 
     Mold sides are closed  1202 ; 
     Bottom casting surface hinges are raised to horizontal  1204 ; 
     Top and bottom cores are inserted  1206 ; 
     All casting surfaces are clean and oiled  1208 . 
     As seen in  FIG. 46 , the stages within the second major stage, Preparing Concrete  1300 , are: 
     Concrete mixer prepares a batch  1302 ; 
     Concrete is transferred to concrete pump  1304 ; 
     The stages within the third major stage, Placing Concrete  1400 , as seen in  FIG. 47  are: 
     Concrete port valves are opened  1402 ; 
     Manifold is clamped down over concrete ports  1404 ; 
     Concrete is pumped into mold cavity  1406 ; 
     Manifold is unclamped and moved to next casting machine  1408 ; 
     Port valves are closed  1410 ; 
     As seen in  FIG. 48 , the stages within the fourth major stage, Waiting for Initial Set  1500 , are: 
     Machine idles until temperature sensors signal initial concrete set  1502 . 
     As seen in  FIG. 49 , the stages within the fifth major stage, Removing Block from Casting Machine  1600  are: 
     Top core is retracted  1602 ; 
     Bottom casting surfaces are hinged down to vertical and mold sides open  1604 ; 
     Bottom core and block are lowered until block contacts conveyor belt  1606 ; 
     Bottom core continues downward, pulling free from block, which is now freestanding on conveyor belt  1608 ; 
     Block exits front of machine and enters initial set heated curing area  1610 ; 
     Casting machine is cleaned with high pressure water or air spray  1612 ; 
     Casting surfaces are oiled with release agent  1614 ; 
     Casting machine is “closed”: 
     Mold sides are closed, 
     Bottom casting surfaces are raised, 
     Top and bottom cores are inserted  1616 ; 
     While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above described exemplary embodiments, but should be defined only in accordance with the appended claims and their equivalents. 
     INDUSTRIAL APPLICABILITY 
     The first embodiment of the present system for fabrication of precast modular blocks  10  is well suited for application in building construction of many kinds. The use of large-scale precast blocks  1  can greatly increase the speed with which buildings can be erected, and can reduce the amount of human labor required. The system of the present invention  10  provides an automated system for the fabrication of precast modular blocks for building construction which is highly efficient and allows the production of much greater numbers of precast modular blocks of a larger size than is possible by use of prior casting equipment and methods. 
     The present invention includes a system for manufacture of precast concrete structural members  10  which includes a production plant  12  housing the system  10 , which includes at least one casting machine  22 , a concrete delivery subsystem  64 , and a block transport subsystem  20 . The casting machines  22  are themselves novel, as they include self-releasing molds  112 , by which the components of the mold remove themselves from contact with the solid initial set concrete blocks  30  automatically. These components are powered by hydraulic or other mechanical mechanisms, which can be operated without human action, thus greatly reducing the labor and cost of the finished units. 
     Generally, wet concrete is prepared in a concrete mixing system  16 , and poured into the concrete hopper  68  which is mounted to the hopper carriage  70 , and moved in position with one of the casting machines  22  by the hopper carriage mover  72 . When the casting machine  22  is in closed position  80 , the mold sides  84 , mold end dams  86 , and bottom casting surface  88  surround a cavity  108  into which the wet concrete will be poured. The mold sides  84 , mold end dams  86 , and bottom casting surface  88 , as well as the top core  92  and bottom core  96  together form the self-releasing mold  112 . Concrete is poured into this self-releasing mold  112  and hardens to its initial set stage while in the casting machine  22 . 
     Then the casting machine  22  moves to an open configuration  78 , during which the newly cast block  30  is freed from the mold  112  of the casting machine  22  and the top core  92  and bottom core  96 . The top core placement assembly  94  includes core lifter hydraulics  114  and a core extractor  116 , which has a top core collar  118  and collar extractor hydraulics  120  and retaining pin  122 . The top core extractor  116  is designed to gently pull up on the top core  92 , while pushing down on the tops of the cast block  30 , so that the top core  92  is removed from the initial set block  30  without tearing the newly set concrete. The mold sides  84 , and mold end dams  86  are then moved away from the cast block  30  so that the sides and ends are free. Lastly, bottom surface panels  150  of the releasable bottom casting surface  88  rotate on bottom surface pivots  126 , and the bottom core  96  is drawn downwards by the bottom core vertical hydraulics  128 . The cast block  30  contacts the block conveyer mechanism  134 , which stops the downward movement of the block  30 , while the bottom core  96  continues downwards until it is free from contact with the block  30 . The block  30  has now been released from the casting machine  22  by the machine&#39;s self-releasing operation. 
     The block  30  is then moved to the initial set heated curing ovens  24 , preferably by a system of conveyer mechanisms  66  which are included in the block transport system  20 . After an initial heated cure operation, the block  30  is then moved to the final curing area  36  where the final curing stage takes place before the completed block  1  is moved to a transport area for shipping. 
     The system  10  is preferably designed with multiple casting machines  22 , which are all served by a single concrete hopper assembly  28 . The concrete hopper  68 , mounted on hopper carriage  70 , is conveyed first to the concrete mixing source  16 , loaded with mixed concrete  26 , and then is moved along the rails  18  of the concrete delivery subsystem  64  until it is positioned by the hopper carriage mover  72  to enter the first casting machine  74 . It then is moved until it is fully positioned in the first casting machine  74 , and delivers the load of wet concrete  26  into the closed mold of the first casting machine  74 . When this operation is completed, the hopper carriage mover  72  withdraws the concrete hopper  68  from the first casting machine  74 , and returns along the rails of the concrete delivery subsystem  64  to the concrete mixing source  16  for another load of concrete. It then moves to the second casting machine  76 , now in closed position, where it delivers the load of concrete. This pattern continues until all casting machines  22  have been filled. Preferably, the number of casting machines  22  is chosen so that the concrete hopper assembly  28  is in continuous operation. 
     The self-releasing operation of the casting machines  22  allows the system  10  to function with a minimum of human intervention. Ideally, the system  10  can be operated automatically so that mixed concrete  26  is introduced at the input and finished precast blocks  1  can be collected from the output. This greatly reduces the labor required and cost of the finished units. This highly efficient system allows the production of much greater numbers of precast modular blocks of a larger size than is possible by use of prior casting equipment and methods. 
     The second presently preferred system for fabrication of precast modular blocks  710  is well suited for application in building construction of many kinds. The use of large-scale precast blocks  1  can greatly increase the speed with which buildings can be erected, and can reduce the amount of human labor required. The system of the present invention  710  provides an automated system for the fabrication of precast modular blocks for building construction which is highly efficient and allows the production of much greater numbers of precast modular blocks of a larger size than is possible by use of prior casting equipment and methods. 
     The present invention includes a system for manufacture of precast concrete structural members  710  which includes a production plant  712  housing the system  710 , which includes at least one casting machine  722 , a concrete delivery subsystem  64 , and a block transport subsystem  20 . The casting machines  722  are themselves novel, as they include self-releasing molds  812 , by which the components of the mold remove themselves from contact with the solid initial set concrete blocks  30  automatically. These components are powered by hydraulic or other mechanical mechanisms, which can be operated without human action, thus greatly reducing the labor and cost of the finished units. 
     Generally, wet concrete is prepared in a concrete mixing system  716 , and poured into the concrete pump  900 . When the casting machine  722  is in closed position  80 , the mold sides  784  and bottom casting surface  788  surround a cavity  108  into which the wet concrete will be pumped. The mold sides  784  and bottom casting surface  788 , as well as the top core  92  and bottom core  96  together form the self-releasing mold  812 . Concrete is pumped into this self-releasing mold  812  and hardens to its initial set stage while in the casting machine  722 . 
     Then the casting machine  722  moves to an open configuration  78 , during which the newly cast block  30  is freed from the mold  812  of the casting machine  722  and the top core  92  and bottom core  96 . The mold sides  784  extend over the top of the cast block  30  and hold it firmly in place so that the top core  92  is removed from the initial set block  30  without tearing the newly set concrete. The mold sides  784  are then moved away from the cast block  30  so that the sides and ends are free. Lastly, the releasable bottom casting surfaces  788  rotate on bottom surface pivots  826 , and the bottom core  96  is drawn downwards by the bottom core vertical hydraulics  128 . The cast block  30  contacts the block conveyer mechanism  134 , which stops the downward movement of the block  30 , while the bottom core  96  continues downwards until it is free from contact with the block  30 . The block  30  has now been released from the casting machine  722  by the machine&#39;s self-releasing operation. 
     The block  30  is then moved to the initial set heated curing ovens  724 , preferably by a system of conveyer mechanisms  66  which are included in the block transport system  720 . After an initial heated cure operation, the block  30  is then moved to the final curing area  36  where the final curing stage takes place before the completed block  1  is moved to a transport area for shipping. 
     The system  710  is preferably designed with multiple casting machines  722 , which are all served by a concrete pump  900  and one or more connected sets of concrete placement boom  901 , concrete delivery hose  902 , and concrete manifold  903 . The manifold  903  is moved to the first casting machine  774 , and the load of wet concrete  26  is pumped into the closed mold of the first casting machine  774 . When this operation is completed, the concrete placement boom  901 , concrete delivery hose  902 , and concrete manifold  903  move to the second casting machine  776 , now in closed position, where another load of wet concrete  26  is pumped into the closed mold of the second casting machine  776 . This pattern continues until all casting machines  722  have been filled. Preferably, the number of casting machines  722  is chosen so that the concrete pump  900  is in continuous operation. 
     The self-releasing operation of the casting machines  722  allows the system  710  to function with a minimum of human intervention. Ideally, the system  710  can be operated automatically so that mixed concrete  26  is introduced at the input and finished precast blocks  1  can be collected from the output. This greatly reduces the labor required and cost of the finished units. This highly efficient system allows the production of much greater numbers of precast modular blocks of a larger size than is possible by use of prior casting equipment and methods. 
     For the above, and other, reasons, it is expected that the system  710  of the present invention will have widespread industrial applicability. Therefore, it is expected that the commercial utility of the present invention will be extensive and long lasting.