Apparatus for forming concrete blocks

Abstract: Apparatus and method for continuously forming concrete blocks or pavers comprises a frame (18) for defining a supporting structure with a mould box flexibly mounted thereon, the mould box having internal cavities contoured to define preselected block patterns, wherein a feed device (12,14) for receiving concrete material is operable for selective positioning over an upper surface of the mould box for investing concrete material into the cavities. First and second sets of vibrators (136,144) are mounted, respectively, generally at opposite ends of the mould box means and are operable for being selectively driven by associated first and second power drives (132,143). The first and second power drives are selectively operable for synchronising or independently actuating the first and second sets of vibrators, respectively, so that concrete material invested into the cavities of the mould box may be vibrated so that the concrete material is evenly distributed in substantially equal masses throughout the cavity in the mould box.

Description: The present invention relates to machines for manufacturing concrete blocks. In the production of concrete blocks, including paving slabs, it is conventional to use large block forming machines which vibrate and compress concrete material dispensed into a mould. After compression, the concrete blocks are stripped from the mould and taken to a suitable curing station, after which time the product is shipped. One type of concrete block forming device is disclosed in US-A-3 343 239. There, a mould box is supported above a pallet holder, suitably mounted in a frame structure, and a single vibrator rod is mounted on opposite sides of the mould box. The vibrator rods are connected to the mould box and, adjacent their lower ends, to a rotatable shaft which imparts vibration to the rods and thus to the mould box. Vibration is used in an attempt to distribute concrete material evenly within the mould box. Other examples of various types of vibrating apparatus for forming concrete blocks are disclosed in US-A-4 193754; 4111627; 3659986; 3331112; 2706320; 2396999; 3712785 and FR-A-2478519. Each of these patents discloses see type of device for vibrating a mould or concrete product to effect a uniform mould fill. Additionally, there are systems which utilise rotatable vibrators connected to a pallet table, such as systems using electric vibrators (motors with eccentric weights built into them) usually in pairs which run in counter-opposing directions. In forming concrete blocks with machines, such as described above, and in those which use some type of feed drawer for filling a mould box, a particular problem resides in that the feed drawer will not distribute concrete material evenly into each of the cavities of the mould box. This is because as a feed drawer passes over a mould box, material which initially is displaced into the first cavities become more compacted than material which is displaced into downstream cavities. Then, when the feed drawer is retracted, it may leave an uneven profile of concrete material in the mould box, i.e. there may be more material at one end than at the other. Therefore, it becomes advantageous to provide some type of vibration material in the mould box, and it may be important to vibrate the concrete material during compression also. FR-A-2478519 attempts to overcome this problem by providing apparatus for continuously forming concrete blocks, said apparatus comprising a supporting frame, a mould box mounted on the frame and having internal cavities contoured to define preselected mould patterns, feed means for receiving concrete materials and operable for selectively positioning over an upper surface of the mould box, for investing concrete material into the cavities, vibration means mounted on said mould box for imparting vibration thereto and power driven means, selectively operable to impart vibration to said vibration means, the mould box being mounted on a first frame to form a block forming section which is symmetrical about a vertical axis, the feed means being in the form of at least one feed drawer mounted on a separate, second frame and movable between a first position remote from said mould box and a second position disposed above said mould box and the vibration means being disposed between the first frame and the mould box. The present invention starts from the disclosure of this document and is characterised in that said second frame is mounted on wheels for enabling movement along a track, so that it may be rolled away from the central block forming section for maintenance or repair and in that a pallet feeder assembly is mounted on said second frame for dispensing pallets upon which concrete product ejected from the mould is received. Such a structure is found to work more satisfactorily and quickly and enables easy maintenance and repair. Furthermore, with the apparatus of the invention, controlled and selected vibration of a filled mould box, at opposite ends thereof, can be achieved to ensure even distribution of concrete material, i.e. that each cavity in the mould box is filled with the same mass of material. Preferably spaced-apart vibrator rods are mounted generally at opposite ends of the mould box and a first pair of vibrator rods is driven by a first power driven means, and a second pair of vibrator rods is driven by a second power driven means. Each of the power driven means may be selectively operably for synchronising or independently actuating the first and second pairs of vibrator rods, respectively. The result is that if it is determined that the mould box is filled unevenly, one of the pairs of vibrator rods may be shut down and the other operated, or in any selected sequence. The point is that each pair is independently driven by a variable speed drive and can be synchronised during all phases of a production cycle or synchronised for a portion of such a cycle, or run independently for the remainder. First and second feed drawers may be mounted adjacent the frame and selectively operable for independent, rectilinear shifting from positions remote from the mould box to corresponding positions thereabove. This means that concrete blocks or pavers may be made having a colour "cap" for decorative purposes. Explaining further, with the sectional design of the present invention, a first feed drawer may be disposed over the mould box for investing material thereinto, and after retraction of that feed drawer, the other may be moved into position for investing different coloured concrete material on top of that already in the mould box. In order that the present invention will be more readily understood, the following description is given, merely by way of example, reference being made to the accompanying drawings, in which:- Figure 1 is a side elevational view of one embodiment of apparatus of the present invention, showing a central block forming section flanked by opposed, feed drawer assemblies; Figure 2 is a view taken along section lines 2-2 of Figure 1, and illustrates in detail the construction of the central block forming section; Figure 3 is an isolated view of one side (facing the viewer in Figure 1) of the central block forming section; Figure 4 is an isolated view of the other side of the central block forming section; Figure 5 is a top plan view, taken along lines 5-5 of Figure 1 and illustrates an isolated view of the central block forming section; Figure 6 is a side elevational view of a first feed drawer assembly; Figure 7 is a view taken along lines 7-7 of Figure 1 and illustrates an end view of the first feed drawer assembly; Figure 8 is a side elevational view of a pallet feed assembly isolated from its normal mounting in the first feed drawer assembly; and Figure 9 is an isolated, schematic view, partially broken away, showing the first feed drawer disposed over the mould box. The illustrated apparatus 10 is formed in sections comprising a first feed drawer assembly 12, a central block forming section 14 and a second feed drawer assembly 16, which is provided for optional capability of producing blocks or pavers having a colour "cap". Block forming section 14 is designed as a self-supporting unit symmetrical about its own centreline, and the first and second feed drawer assemblies also are individual and separate units which are mounted on power-driven wheels so that they may be rolled away for easy maintenance. As shown in Figure 1, the block forming section 14 includes a box-like frame 18, which includes interconnected upright members and cross-beams, etc. It will be noted that frame 18, which includes a base 20, is mounted on vibration isolators 22. As shown in Figure 2, block forming section 14 is provided with a pair of opposed, upstanding guide columns 24,26 which slidably receive a transversely-extending compression beam 28 and a main or stripper beam 30 disposed therebeneath, provided with bushings 32,34 and bushings 36,38 respectively. Compression beam 28 is provided with a plurality of downwardly extending shoes, such as indicated at 40-48 which are configured for compressing concrete material and ejecting the formed product from the cavities in a mould box in a manner to be described. Each of the shoes is provided with a base plate, such as indicated at 40a, 42a etc. Dashed line A shown adjacent top of Figure 2 represents the maximum extent to which compression beam 28 will be raised, and at that point, the positions of base plates, such as indicated at 40a, 42a etc are shown in dashed lines also. Mounted on opposite ends of stripper beam 30 are fluid-actuated cylinders 50 and 56 and associated piston rods 52,58 operable for vertically shifting compression beam 28 relative to the stripper beam. Air bags 54,60 provide vibration isolation and cushion the action of compression beam 28 and its associated components in operation. Additional bushings 62 and 64, mounted on frame 18, are provided for slidably receiving guide columns 24,26 respectively. Mounted on the left and right sides of compression beam 28 are downwardly extending projections 66 and 70 bolted thereto which will engage stops 68 and 72 to limit the extent to which the compression beam can be moved downwardly. Further, it will be noted that stripper beam 30 is vertically shiftable relative to the frame 20 by means of stripper cylinder/rod assemblies 74,76, mounted adjacent opposite ends of the stripper beam. As illustrated in Figure 2, as well as in Figures 1 and 3, 4, stripper beam 30 is in its fully retracted position. The cylinder/rod assemblies 74,76 are mounted so that their associated rods 74a,76a engage the stripper beam and are operable for selectively raising and lowering the stripper beam. It will be noted that stripper beam 30 supports a pallet table 78 which in turn provides a mount for a pallet 80, for receiving concrete blocks or pavers and typically is formed from 12.7 mm (½") steel plate. The pallet table is mounted by means of vibration isolators, such as air bags 82-88 on a saddle 90 which, in turn, is mounted on the stripper beam by means of spacer/bracket assemblies 92,94 and 96. Attention will now be directed to the specific construction of the vibration means which is positioned in block forming section 14 and suitably connected to a mould box for imparting vibration thereto. A mould box is shown in cross-section at 100 in Figure 2, with internal cavities 102-110 contoured to define preselected block or paver patterns. The mould box is suitably mounted, at opposite sides thereof, to spaced-apart guide supports 112,114, which are, in turn, non-rigidly and flexibly mounted on the frame by elongate, metallic plate springs 116,118,120,122 (see Figures 2, 3 and 4) which may flex. As shown at the bottom left of Figure 2 (see Figure 4 also), a first power driven means 124 is mounted on the frame, and is interconnected by a timing belt drive 126 to a vibrator housing 128 which includes an internal eccentric arrangement for imparting vibration to a vertically extending vibrator rod 130, which is bolted to guide support 112 as shown. Viewing the bottom of Figure 2, it can be seen that a horizontally extending first shaft 132, which is driven by first power driven means 124, extends from vibrator housing 128 to vibrator housing 134 which in turn is provided with an eccentric arrangement to impart vibration to vibrator rod 136 which is bolted to guide support 114. Similarly, a second power driven means 138 (see Figure 4) is suitably coupled to a vibrator housing 140 for imparting vibration to vibrator rod 142 and, via a second shaft means 143, imparting vibration to vibrator rod 144 (see Figure 3). Thus, what has been described are first and second sets of vibrators mounted, respectively, generally at opposite ends of the mould box. The vibrators are defined by a first pair of spaced-apart, vertically extending vibrator rods 130,136 each having one end thereof connected to the mould box and the other end to first power driven means 124. The second set of vibrators is defined by a second pair of spaced-apart vertically extending vibrator rods 142, 144, each also having one end thereof connected to the mould box and the other to second power driven means 138. It can be appreciated that the first pair of vibrator rods 130,136 can either by synchronised or operated independently from the second pair of vibrator rods 142,144. This becomes important when it is understood that it is desirable to have the flexibility of imparting vibration to the mould box, after it has been filled, or to impart vibration to one end of the mould box as will become apparent when the operation of the apparatus is described later. With reference again to Figure 1, the first feed drawer assembly 12 is mounted on a frame structure which in turn is mounted on wheels 146,148 for enabling movement along a track, thereby to shift the assembly away from central block forming section 14 when it is desired to clean or maintain the unit. As shown in Figure 6, first feed drawer assembly 12 comprises a normally stationary box 150 having a hopper 152 mounted thereon. Extending from opposite sides of box 150 are arms 154 (see also Figure 7) which are journalled to a pair of wheels 156,158 on each side, which are movable along associated tracks, such as tracks 160,162 as shown in Figure 7. Disposed beneath box 150 is a relatively shiftable first feed drawer 164, which is provided with a vertically adjustable "strike-off" or screed plate 166. Additionally, the first feed drawer is provided with wheels 168, 170 and counterparts thereof on the opposite side, such as wheel 169. The wheels ride on tracks 172,174 as also shown in Figure 7. An elongate agitator rod 173 is suitably connected via a series of pivotally connected links 175, 176 and 178 which are in turn connected to agitating fingers disposed inside the first feed drawer. Agitator rod 173 is driven by a motor 180 which is connected to an eccentric pulley 182 thereby to oscillate the links and the fingers to agitate concrete material inside feed drawer 164 and box 150. It will also be noted that motor 180 and eccentric pulley 182 are mounted on a frame which includes rear wheels 184, for travel along tracks 172, 174. A fluid powered cylinder 186 is operable for extending and retracting a rod 188 and an associated engaging element 190 for selectively extending the first feed drawer to the left relative to box 150, when viewing Figures 1 and 6, and for returning the feed drawer to the position shown in Figure 6. The idea is that concrete material will be dispensed into hopper 152 and box 150 and then into the feed drawer. The feed drawer is bottomless but concrete material is retained by a plate provided on the frame structure when the feed drawer is positioned to the right as shown in Figure 6. When the feed drawer is shifted to the left so that it is positioned over mould box 100, concrete material will be invested thereinto as will be described. Figure 2 shows first feed drawer 164 has travelled along tracks 172,174 to a position over the mould box. Returning to Figure 1, it will be noted that track 172 is shown extending through central block forming section 14 and to the left of Figure 1, the second feed drawer assembly comprises a structure similar to that just described for the first feed drawer assembly 12, except it does not include a pallet feeder assembly such as generally indicated at 200 in Figure 1. Pallet feeder assembly 200, shown in greater detail in Figure 8, comprises a lifting means 202 which will receive pallets, such as indicated at 80, 81 etc. The lifting means is powered by a lifting cylinder/rod assembly 206 so that the pallet may be shifted upwardly, as indicated by the arrows so that the pallet will be raised to the position indicated at 80a. Thereupon, a pusher rod 208 is selectively actuated by a power driven cylinder 210 to engage an end of the pallet and shift it to the left, so that the pallet will be displaced onto the pallet table 78. It is also to be noted from Figures 1 and 6 that a motor 212 is suitably interconnected via a gear box 214 and transmission means 216 to wheel 146 so that the first feed drawer assembly 12 and supporting frame may be shifted away from central block forming section 14. A similar construction is provided for second feed drawer assembly 16. As shown in Figure 6, a locking/release mechanism interconnecting the systems is shown at 218. Lastly, while rail 172 is shown in Figures 1 and 6 as being continuous, the rails will in fact be comprised of separate, alignable sections to enable the first and second feed drawer assemblies to be shifted away from central block forming section 14 when maintenance or repair is required. Conventional control devices, hoses, wiring etc are provided to control operation. The method of operation of the apparatus of the present invention, in the forming of concrete blocks, provides several distinct and important advantages. In one mode of operation, where a colour cap is not provided, the steps generally are as follows. First, with reference to Figure 2, it will be noted that stripper beam 30 is retracted via cylinders 74,76 into its lowest position. Cylinders 50,56 are actuated so as to extend their corresponding rods 52,58, respectively, to displace compression beam 28 so that it extends to the position indicated at A in Figure 2. With the stripper beam in its lowest position, pallet feeder assembly 200 is actuated to shift a pallet onto pallet table 78. A pallet is disposed in that position as shown in Figures 2-4. At that point, cylinders 74,76 are actuated to displace stripper beam 30 vertically, so that the top of pallet 80 is positioned directly beneath mould box 100. First feed drawer 164, filled with concrete material, is then shifted toward block forming section 14, i.e. to the left with reference to Figures 1 and 6. At the front edge of the screed plate of the first feed drawer begins to pass over the leading edge 100a of the mould box (see Figure 3), concrete material is dispensed into the first cavities of the mould box, and as the first feed drawer continues moving over the mould box, the remaining cavities are filled with concrete material. During the investing step, agitator rod 173 is actuated so that the concrete material is continuously stirred up. Figure 2 shows positioning of first feed drawer 164 over mould box 100 after the first feed drawer has travelled along rails 172,174. Because the feed drawer is bottomless, it has displaced concrete material into the individual cavities, such as those indicated at 102,104,106 etc. The concrete materials fills each cavity substantially, and pallet 80 forms a bottom retainer. An enlarged and broken-away schematic view of the first feed drawer above the mould box is shown in Figure 9. As can be seen, the mass of concrete material will not be evenly distributed in each cavity, inasmuch as those cavities which are initially filled will have a greater density than those subsequently filled. That is because the concrete material within the first feed drawer is deepest over the initially filled cavities, resulting in a denser mass there. Specifically, the density of concrete material will be less in the cavities to the left, such as indicated at 100. Those cavities closest to the leading edge 100a of the mould box will have a more dense initial compaction of concrete material. However, it is desired to even out the densities in the cavities, so that each contains an equal mass of material. Accordingly, with the first feed drawer disposed over the mould box during the investing step (as shown in Figures 2 and 9), first and second power driven means 124,138 are now actuated to impart vibration to first pair of vibrator rods 130,136 and second pair of vibrator rods 142,144, respectively. As a result of the vibration, concrete material is vibrated and shifted so that it becomes more evenly displaced in the cavities. Nevertheless, if an operator determines that the concrete material is not evenly distributed, or if it is desired to redistribute that material or change its profile within the mould box, then the second pair of vibrator rods 142,144 may be deactuated while the first pair of vibrator rods 130, 136 continues in operation. Vibrator rods 130, 136 are furthest from the cavities which were initially filled, and continued operation of those rods results in more vibration in the downstream end of the mould box ensuring more even distribution of material. This may be accomplished with feed drawer 164 positioned above mould box 100. Either pair of vibrator rods may be actuated, with the other shut down, to achieve a desired distribution of concrete material. Next, after first feed drawer 164 is retracted, so that screed plate 166 drags excess material rearwardly (or to the right when viewing Figure 1), the pair of vibrator rods may be run independently or simultaneously to "profile" the material as desired in the mould box. Alternatively, during retraction of the feed drawer, neither pair of vibrator rods may be operated. The point here is that an operator has the capability of selectively operating the system to command a desired profile in the mould box. After first feed drawer 164 has been fully retracted, the compression step occurs as follows. Compression cylinders 50,56 are actuated to retract their associated rods 52,58 to a position whereby shoes 40a,42a etc are directed downwardly into the cavities of mould box 100 to compress and compact the concrete material. During this compression stage, typically all four of the vibrator rods may be driven for vibration of the mould box, or alternatively, a selected pair may be activated while the other pair is shut down. In any case, it is contemplated that it is preferable to provide vibration and compaction simultaneously, and synchronisation or independent operation of the first and second power driven means is possible depending upon the circumstances. After compression beam 28 has been lowered to the position whereby projections 66,70 engage corresponding stops 68,72, cylinder/rod assemblies 74,76 are actuated to lower pallet table 78 which thereby receives the compacted and formed blocks or pavers, such as shown at B, these products now being "stripped" from the mould box. Another process utilising the present invention contemplates producing blocks or pavers having a different coloured top or colour "cap". To that end, first feed drawer 164, provided with base material of concrete, initially invests or fills the mould box. Vibration means 98 may be suitably actuated to provide vibration, as described above. After first feed drawer 164 has been retracted, the feed drawer of second feed drawer assembly 16, filled with concrete material having a different colour, is shifted into position so that the new material is dispensed on top of the original base material, thereby providing a colour cap. The second feed drawer is withdrawn, and compression beams and stripper beams are then actuated for providing the compression and strip-off steps, as described above. Again, vibration may be provided as needed whenever necessary. Pavers having such a colour cap are highly decorative, and find many applications in sidewalks, mall areas etc. The pairs of vibrator rods are mounted on their associated eccentric drives so that they can travel over a range of 2 mm from the bottom dead centre (BDC) to top dead centre (TDC). Thus, the mould box can correspondingly be moved that distance, or by suitable command, some selected shorter distance. Further, one end of the mould box may be moved relative to the other by suitably commanding operation of a selected pair of the vibrator rods. An operator has flexibility to adjust the distribution of concrete material in the mould box to provide even distribution. The profile of the concrete material can be varied as the feed drawer is retracted. It is important to note that it is the mould box which has vibration imparted thereto. It will be noted that the apparatus provided has a sectional design, i.e. a central block forming section is positioned between first and second feed drawer assemblies, and all three are separable enabling only one or other feed drawer to be used. Because the first and second power driven shafts of the vibration means turn in counter opposing directions, a balanced design results, and contributes to accurate mould fill and product compression characteristics. A principal advantage of the present invention is the mounting of first and second pairs of vibrator rods which are secured to the mould box, generally at opposite ends thereof. With each of the first and second pairs being driven by its own independent power driven means, in counter-opposing direction, each pair may be synchronised with the other or operated independently. This means that if a mould box is filled unevenly, one of the pairs may be operated for a longer cycle than the other. The goal is to place the same mass of material in each cavity of the mould box, and to even out densities of material in those cavities. The density profile of concrete material which remains in the mould box, after retraction of the feed drawer, can be evened out even further during compression, i.e. the vibrator rods can be actuated during the actual compression step wherein the compression beam moved the shoes against concrete material during compression. Another advantage of the present invention resides in the provision of rails or tracks which extend from one feed drawer assembly through the central block forming section and continue on into the second feed drawer assembly. It is not necessary that the rails, such as indicated at 172,174 actually form continuous members, but rather that a rail system is provided so that feed drawers which are laterally opposed on opposite sides of the mould box may be operable for rectilinear shifting therealong from a first position remote from the mould box to a second position disposed directly thereabove so that the investing step may take place. It is important to note that the positioning of rails 172, 174 effectively isolates the feed drawers from the mould box. Because the mould box, in turn, is located in position by flexible mounts such as plates 116,120, vibration imparted to the mould box essentially is not imparted to the rails and the feed drawers. This is important because if a feed drawer is vibrated, the material therewithin becomes more compacted, so that it will not flow as readily therefrom into the mould box. While selected operational times are available, a typical sequence might involve imparting vibration during the investment step for approximately 2-3 seconds. After investment, only one pair of the vibrators may be run for about 1 second. Different sequences are available according to type of concrete material, etc.

Claims: Apparatus for continuously forming concrete blocks, said apparatus comprising a supporting frame (18), a mould box (100) mounted on the frame and having internal cavities (102-110) contoured to define preselected mould patterns, feed means (12,16) for receiving concrete materials and operable for selectively positioning over an upper surface of the mould box (100), for investing concrete material into the cavities (102-110), vibration means (130,136,142,144) mounted on said mould box for imparting vibration thereto and power driven means (124,138), selectively operable to impart vibration to said vibration means, the mould box (100) being mounted on a first frame (18) to form a block forming section (14) which is symmetrical about a vertical axis, the feed means (12,16) being in the form of at least one feed drawer (150) mounted on a separate, second frame and movable between a first position remote from said mould box and a second position disposed above said mould box and the vibration means (130,136,142,144) being disposed between the first frame (18) and the mould box (100), characterised in that said second frame is mounted on wheels (146,148) for enabling movement along a track, so that it may be rolled away from the central block forming section (14) for maintenance or repair and in that a pallet feeder assembly (200) is mounted on said second frame for dispensing pallets (80,81) upon which concrete product ejected from the mould is received. Apparatus according to claim 1, characterised in that the apparatus includes a third frame, separate from said first and second frames, and which is also isolated from said first frame during the vibration phase of the mould on which is mounted a second feed drawer (150), said second feed drawer being movable between a first position remote from said mould box and a second position disposed above said mould box wherein said second feed drawer may be used wholly in place of said first feed drawer. Apparatus according to claim 2, characterised in that the second and third frames are positioned on opposite sides of said first frame. Apparatus according to claim 1 or 2, characterised in that the mould box (100) is non-rigidly and flexibly mounted on the first frame (18) by metallic plate springs (116,118,120,122). Apparatus according to any preceding claim, characterised in that said vibration means comprises first and second sets of vibrators (130,136 and 142,144) mounted on generally opposite ends of said mould box. Apparatus according to claim 5, characterised in that said power driven means comprises first and second power driven means (124,138) in that the first set of vibrators is defined by a first pair of spaced-apart, vertically extending vibrator rods (130,136) each having one end thereof connected to the mould box and the other end to the first power driven means (124) and in that the second set of vibrators is defined by a second pair of spaced-apart, vertically extending vibrator rods (142,144) each having one end thereof connected to the mould box and the other to an associated second power driven means (138).

Inventors: ALLISON J DENNIS, SCHMITT ROBERT A, ALLISON, J. DENNIS, SCHMITT, ROBERT A.
Applicants: COLUMBIA MACHINE, COLUMBIA MACHINE INC
Application year: 1990
Main classification: B28B1
IPC codes: B28B13, B28B3, B28B1