WO1982002510A1

WO1982002510A1 - System for molding blocks

Info

Publication number: WO1982002510A1
Application number: PCT/US1982/000038
Authority: WO
Inventors: Equipment Co Builders; Paul Michael Thomas; Daniel Paul Abrahamson
Original assignee: Builders Equip Co
Priority date: 1981-01-16
Filing date: 1982-01-15
Publication date: 1982-08-05
Also published as: JPS57502255A; WO1982002509A1; AU8146682A; AU8146782A; EP0069771A1; JPS57502160A; EP0069770A1; ES508770A0; EP0069771A4; EP0069770A4; ES8304469A1

Abstract

A system for molding masonry blocks. A pallet (22) is deposited upon a bed (24). A mold box (40) carried by a cradle (50) is lowered onto the pallet (22) by deflation of a lift system (74). When the mold box (40) is deposited upon the pallet (22), a laterally reciprocating feed drawer (144) moves to a position above the mold box (40) to deposit mix within the mold box. The feed drawer (144) returns to a loading position, drawing a laterally reciprocating head (140) into position above the mold box. A compression system comprising a plurality of inflatable chambers (173) operate upon a plurality of vertically arranged platforms (177, 179, 187 and 194) to compress the mix. After compression, the mold box (40) is stripped by inflation of the lift system (74).

Description

SYSTEM FOR MOLDING BLOCKS

Technical Field:

The present invention relates to a method and apparatus for the manufacture of molded building blocks, bricks or the like. Background Art:

In the manufacture of blocks used in the construction of buildings, for example, a mixture of a binder, such as cement, water and aggregate is deposited into a mold. The mold includes a mold box having a peripheral wall, one or more solid cores which define large cavities within the finished block and a pallet upon which the mold box rests. Thereafter, the mold box, pallet and, in some cases the cores, are vibrated to settle the mixture within the mold and around the cores and to drive out entrained air. Then a ram compresses the block to drive out additional air. The compression serves to strengthen the block as well as ensure consistent dimensions in the finished block.

It is a common practice in the block-making art to use about twice the necessary amount of hydration water in the mix. Approximately 0.25 to 0.30 pounds (114 to 135 grams) of water is all that is required to hydrate one pound (455 grams) of cement, for example. By adding an excessive amount of water to the binder and aggregate mixture, the mixture becomes easier to form. However, the excess water does not further hydrate the cement, but rather merely forms water pockets within the block. The water pockets eventually dissipate, but they leave behind voids in the block. These voids weaken the finished block, an undesirable result which block manufacturers have accepted heretofore rather than incur tie additional expense required heretofore for increased compressive forces. In prior block machines wherein compression is achieved by means of mechanical cams or hydraulic cylinders, for example, the pressures economically available for compressing the blocks have been limited to levels of about 100 pounds per square inch (7 kilograms per square centimeter) of block surface. At such low pressures prior machines have left a void volume of about 6 per cent. It has been determined, however, that a reduction in void volume of just one percent can permit a reduction in cement content of five to eight percent. The cost savings are readily apparent. Moreover, such prior block making machines are incapable of producing the forces necessary for manufacturing paving brick, for example.

Two important ways by which the production cost of a block can be reduced are to reduce the costs of materials, and to increase the speed of production. By reducing the amount of water used for a given block, reducing the void volume and reducing the cement content, the materials cost of a block is reduced.

Within a block machine there are several different motions which, must occur sequentially. That is, one portion of the machine must wait to move into position until a prior operation by another portion of the machine is completed. This waiting period can be reduced through higher speed or reduced distances of travel. Generally speaking, higher speed requires more rapid acceleration and deceleration, which, create shocks within the machine. Although a cured concrete block is extremely strong, a newly formed, or "green", concrete block is relatively fragile. Shocks to the machine can easily cause fractures to develop fissures within the block. It is therefore more desirable to reduce the distance of travel for machine parts rather than speed their travel.

Another aspect of block manufacture which, has been a consistent problem has been the detrimental effects of vibration. Although vibration is important for properly filling the mold box as the mixture is deposited from above, when a mold box is vibrated to settle the mixture, the entire machine usually vibrates as well. Efforts have been made to dampen this machine vibration and isolate the vibration from the more sensitive parts of the machine. Nevertheless, the repetitive initiation of vibration, particularly vibration of the mold box, causes loosening and wearing of the machine parts.

As a result, prior machines have required frequent maintenance, repairs and parts replacement. By limiting the vibrations to a very small portion of the block machine, such as the cores, for example, the remainder of the machine requires substantially less maintenance and repair.

Another problem resulting from intermittent vibration is the high, noise level developed by the frequent starting and stopping of the vibrators. Also, vibrating pallets create a "chatter" which is quite distrubing. In the work environment the noise level is a very important concern. Employees working in the vicinity of prior block machines have suffered from the high noise levels produced. It is important that the noise level be minimized.

The ever-present dust and grit is another aspect of the block-making environment which causes problems with all machinery subjected thereto. In block machines, operated mechanically or by hydraulic cylinders, dust and grit usually become lodged between any two moving parts and cause wearing of the parts. Worn parts require frequent maintenance and parts replacement. Disclosure of Invention:

It is therefore an object of the present invention to provide a system for making masonry blocks. It is also an object to provide a system for making blocks containing a minimal amount of water and requiring reduced amounts of binder. It is also an object to provide a block machine which, requires a minimal amount of maintenance and parts replacement. it is a further object to provide a block machine having reduced noise levels. It is a still further object to provide a system for economically compress blocks at pressures of about 1,000 p.s.i. (70 kilograms per square centimeter). Generally, in accordance with the present invention, a pallet is deposited upon a stationary bed and a mold box and core assembly, carried by a cradle, are lowered onto the pallet by the deflation of a fluid extended lift system. When the mold box and core assembly are deposited upon the pallet, a laterally reciprocating feed drawer is moved to an unloading position above the mold where a predetermined amount of a mix is deposite into the mold. The feed drawer then returns laterally to a loading position. A head, adapted to matingly engage the mold box and core assembly, is attached to the feed drawer to laterally reciprocate therewith, whereby the head is located over the mold when the feed drawer is in the loading position. A compression system comprising a plurality of vertically arranged fluid-extendible chambers operate upon a unitary ram to compress the mixture contained within the mold between the pallet and the head. After compression, the mold box and core assembly are lifted by means of the fluid extendible lift system, to strip the mold box and cores from the green block. The head is then raised from the green block by deflation of the compression system. The pallet, carrying the newly formed, green block, is removed from the bed and a new pallet is deposited upon the bed. The apparatus operates at an extremely low noise level, uses a small amount of power and produces a stronger block having a reduced moisture and binder content. Brief Description of Drawings: FIGURE 1 is a right side elevational view of an apparatus embodying various of the features of the present invention.

FIGURE 2 is an elevational view taken along line 2-2 of FIGURE 1. FIGURE 3 is an elevational view of a compression system, in expanded and deflated conditions, embodying various of the features of the present invention.

FIGURE 4 is an elevational view of a mold lifting system, in expanded and deflated conditions, embodying various of the features of the present invention.

FIGURE 5 is a schematic diagram of an inflation system adapted for the apparatus depicted in FIGURES 1 and 2.

FIGURE 6 is a perspective view of a core assembly embodying various of the features of the present invention. Best Modes for Carrying Out the Invention:

The depicted block machine 10 includes pallet advancing means 12, mold lifting means 14, mixture feeding means 16, and compressing means 18.

The pallet advancing means 12 comprises a magazine 20 containing a vertical stack of pallets 22 located below the level of the stationary bed 24. Means are provided for incrementally raising the stack of pallets 22 as successive pallets are removed from the top of the stack by a reciprocating cart 26. The cart 26 is carried on rails 28 and includes arras 30 adapted to engage the rear edge of the uppermost pallet 22 of the stack and pull the pallet 22 into a channel 32 leading to the bed 24 of the block machine 10. As the uppermost pallet 22 is pulled off the stack, the preceding pallets located within the channels 32 are pushed toward the bed 24 in the channels 32, ejecting the pallet located on the bed 24, carrying previously formed green blocks, and depositing an empty pallet on the bed 24.

The cart 26 is reciprocated by means of an electric motor and gear box (not shown) through a first connecting arm 34 and a second connecting arm 36. The arm 36 is pivotally attached to the arm 34 and to the cart 26, whereby rotation of the arm 34 causes the cart 26 to move reciprocatingly along the rails 28. The circular motion of the arm 34 causes the relatively slow acceleration and deceleration of the pallets 22 with a rapid interim speed within the channels 32. As noted hereinabove, the newly formed green blocks are quite sensitive to rapid acceleration. The relatively slow acceleration and deceleration of the pallet carrying the newly-formed blocks reduces the likelihood of fracture. The arms 30 slope inwardly along the distal edge 38, whereby after the cart 26 has drawn a new pallet into the channels 32, the arms 30 ride up over the top of the next succeeding pallet 22 of the stack as the stack is raised for removal of the successive pallet 22.

Lifting means 14 are provided for depositing a mold box 40 and core assembly 42 upon a pallet 22 resting on the bed and for stripping the mold box 40 and core assembly 42 from green blocks after formation. The mold box 40, comprises a planar front wall 43, an opposing planar back wall (not shown), a pair of opposing planar side walls 44 and 46 and a plurality of partition walls 47 for separating adjacent blocks within a single mold box 40. In the embodiment depicted in FIGURE 2, six blocks are formed within a single mold box 40. The walls of the mold box 40 extend to a height of about 8.25 inches (21.2 cm), about 0.25 inch. (0.6 cm) above the height of the desired blocks. The side walls 44 and 46 of the mold box 40 include attaching flanges 48 which extend laterally for attachment to the cradle 50.

The core assembly 42 which defines the large cavities in the finished blocks includes a rigid right side member 52 and a rigid left side member 54 , each of which carries a onethird horsepower oscillatory vibrator 56 on the outer surface thereof. The members 52 and 54 are interconnected at each end by a pair of threaded rods 58 having a length greater than the width of the mold box 40. A pair of core members 60 are provided for each block to be formed in the mold box 40. Each pair of core members 60 is carried by an elongated core support bar 62 having a pair of spaced-apart apertures (not shown) defined at each end. The apertures in the core support bar 62 are adapted to receive the rods 58. Spacers 64 are coaxially mounted upon the rods 58 to maintain the core bars 62 in fixed relation to one another when nuts are mounted upon the threaded ends of the rods 58 after passage through the members 52 and 54. The two opposing vibrators 56 develop a vertical vibration in the core assembly 42. Vibration is transmitted from the side members 52 and 54 to the cores 60 through the spacers 64 and core bars 62.

The core assembly 42 fits around the outer surface of the mold box 40, resting upon resilient isolators 66 mounted upon the cradle 50. The cores 60 extend into the mold box 40 to a level about 1/64 inch (0.4 mm) above the lower edge of the mold box 40. Thus, the core assembly 42 does not contact the pallet 22 resting on the bed 24. Resilient isolators 68 are also mounted upon the interior corners of the core assembly 42 to prevent direct metallic contact between the core assembly 42 and the mold box 40. Thus, the vibrating core assembly 42 is essentially isolated from the remainder of the apparatus 10 and vibration is not transmitted thereto. The machine 10 may be further isolated from vibration by applying nylon isolators 69 to the upper surface of the bed 24, under the pallet 22. The mold box 40 and core assembly 42 are lifted from, and lowered onto, the pallet 22 by means of the generally U-shaped cradle 50, which includes a pair of vertically oriented arms 70 located at each end of a horizontal member 72. The cradle 50 is mounted upon two fluid extendible lift assemblies 74, which in turn rest upon the base 76 of the main frame 78. Vertical extension of the lift assemblies 74 causes the arms 70 of the cradle 50 to lift the mold box 40 and core assembly 42 about nine inches (23 centimeters) above the pallet 22 to an upper position. Spring means are provided for returning the lift system to a deflated, lower position.

The mold box 40 and core assembly 42 are lifted from the pallet 22 after green blocks have been molded and compressed therein. The frictional resistance to separating the mold box and. cores from the green block is initially quite high. However, once relative movement begins, the frictional resistance between the mold box 40 and cores 60, and the newly formed block is reduced substantially. Therefore, in order to overcome the high initial resistance, large area, lowdisplacement primary chambers 80 are combined with, secondary, small area, high-displacement chambers 83 in the lift assemblies 74.

The lift assembly -74 comprises a primary filler tube: 82 which connects a selectively pressurized tank. 84 of water with the extendible primary chamber 80 defined by a rigid upper plate member 86, a rigid lower plate member 88 and a flexible air-impermeable bellows member 90 sealingly attached to the plates 86 and 88 by bolts seated in the bellows 90 and extending through holes defined in the plates 86 and 88.

Rigid spacer means (not shown) are provided between the upper plate 86 and lower plate 88 to prevent complete collapse of the chamber 80. In the depicted embodiment, the primary bellows 90 comprises an Airmount Airstroke No. 134-1.5, availabl from the Firestone Rubber Company.

The lift assembly further comprises a secondary filler tube 92 connecting the tank 84 with an extendible secondary chamber 83 defined by a rigid upper plate 94, a rigid lower plate 96 attached to the primary chamber upper plate 86 and an air-impermeable flexible bellows 98 sealingly attached to the plates 94 and 96 by bolts seated in the bellows 98 and extending through holes defined in the plates 94 and 96. Rigid spacer means (not shown) are provided between the upper plate 94 and lower plate 96 to prevent complete col lapse of the chamber 83. In the depicted embodiment, the secondary bellows 98 comprises an Airstroke No . 312 available from the Firestone Rubber Company. The chambers 80 and 83 are vertically inflated, or extended, by the introduction of water , under pressure, to cause the cradle 50 to lift the mold box 40. and core assembly 42 from the bed 24 and the pallet 22 resting thereon. The large area of the two chambers 80 provides a large initial force of about 100 , 000 pounds (45 metric tons ) to initiate movement of the mold box 40 and core assembly 42. Vertically adjustable stop means 100 prevent vertical expansion of the chambers 80 for more than about one inch (2. 5 cm) . During the remainder of the lift, necessary to raise the mold box 40 and core assembly above the newly formed block to release the newly formed block , lesser forces are required . Therefore, the smaller area of the secondary chambers 83 provides sufficient force to complete the additional eight inches (20.5 cm) of lift to clear the newly formed block. The cradle 50 is biased to the lowered position in which the mold box 40 contacts the pallet 22 by resilient coil spring assemblies 102. There are four spring assemblies 102 , one assembly being located at each, corner of the cradle 50. The assemblies 102 are substantially identical, so that only one of the assemblies 102 will be described in detail , withan understanding that the description applies to the remaining three assemblies 102 as well .

Each spring assembly 102 includes a vertical core rod 104 , threaded at each end and secured to the main frame 78 at the base 76 and to a laterally extending flange 106 of the main frame 78 . The rod 104 is slidingly received by a horizontal foot 108 of the cradle 50. Three coaxial coil springs 110 , each about 11.5 inches (29. 5 cm) in length and about four inches (10 . 3 cm) in diameter, are mounted upon the rod 104 , extending between the flange 106 and the foot 108 . Alignment rings 112 are located between adjacent springs 110. Each spring 110 provides an expansion force of about 1 , 000 pounds (454 kg) when compressed to a length of about 8. 5 inches (21. 8 cm) .

The lowermost spring 110 rests directly upon the foot 108 and is retained in position by a ring 114 secured to the foot 108. As the cradle 50 is lifted by the lift assemblies 74, the uppermost spring 110 is prevented from rising by a cap 116 mounted upon the rod 104. The cap 116 is adjustably retained in position by means of a nut 118 threaded onto the rod 104 below the flange 106. Vertical adjustment of the cap 116 varies the speed at which the corresponding corner of the cradle 50 is raised by expansion of the lift assemblies 74. That is, by lowering the cap 116 on the rod 104, the springs 110 are compressed to provide increased resistance to the lifting of the corresponding corner of the cradle 50.

The chambers 80 and 83 are expanded by the introduction of pressurized water from the tank 84 which, is partially filled with water. The tank 84 resembles an inverted "A", having a tubular cross-member 120. The tank 84 includes a primary water port 122 at the bottom of the tank. 84 and a secondary water port 124 in the cross-member 120. The port 122 is connected to the filling tube 82. The port 124 is connected to the filler tube 92 by a two inch diameter flexible hose 126 to accomodate vertical motion of the filler tube 92, induced by the extension of the primary chamber 80.. An air port 130 is located at each upper end 132 of the tank. 84. Each of the air openings 130 is connected to a tubular gas accumulator 134 through a two-way safety valve 136 and a three-way valve 138. The accumulator 134 is supplied with air at 100 p.s.i. (7 kg per square centimeter) through an inlet 139 by an air compressor (not shown). In the operation of the lift assembly 74, when the cradle 50 is to be lifted, the valve 138 is opened to permit air flow from the air accumulator into the tank 84. The incoming air forces water from the tank 84, through the ports 122 and 124, and into the filling tubes 82 and 92 to simultaneously expand the chambers 80 and 83, respectively. The bed 24 operates as an upper stop for the cradle 50. When the cradle

50 is to be returned to the lowered position, the air valve

138 is turned to the venting position to release the pressurized air in the tank 84. The extension of spring assemblies 102 causes the cradle 50 to compress the chambers 80 and 83 and force the water contained therein back into the tank 84 throughthe filler tubes 82 and 92, respectively. When the cradle 50 reaches the lowered position, as indicated by contact with, a limit switch, for example, the valve 138 is again closed. The spacer means located within the chambers 80 and 83 operate as a lower stop for the cradle 50.

The compressing means 18 are provided for compressing the mix to the size of the desired finished block after it has been deposited in the mold box 40 by the feed drawer 144 and settled around the cores 60. The compression system includes a head 140 and a vertically movable ram 142. The head 140 is carried upon a pair of horizontal roller tracks 146 secured to the ram 142. The head 140 is attached to the feed drawer 144 by an arm 148, whereby reciprocating lateral movement of the feed drawer 144 causes the head 140 to reciprocate between a position over the mold box 40 and loading position laterally spaced from the ram 142 and mold box 40. The arm 148 is pivotally connected to both the feed drawer 144 and the head 140 to compensate for the vertical motion of the head 140 during compression.

The head 140 is adapted to matingly receive the mold box 40 and core assembly 42 during compression and as they are vertically stripped from a green block. The head 140 comprises a plurality of members 150, each, member 150. being shaped in horizontal cross-section like one-half of a block. The core members 150 are spaced apart to define slots adapted to precisely fit around the core members 60, core bars 62 and partition walls 47 as the mold box 40 and core assembly 42 are stripped. The head 140 has an overall lateral, crosssection which is slightly smaller than the interior dimensions of the mold box 40. The close sliding contact between the head members 150 and the mold box 40 and core assembly 42 provides complete compression of the mix by the ram 142 and prevents distortion of the green block as it is stripped. Moreover, the head must be raised and lowered only a minimal distance of about an inch (2.5 cm). The core bars 62 and partition walls 47 extend vertically above and laterally beyond the mold box 40 and core assembly 42. As a result, the core bars 62 and partition walls 47 never become completely disengaged from the slots defined between the head members 150 , despite the vertical and lateral motion of the head 140. Slots are defined in the feed drawer 144 to slidingly receive the upper portions of the core bars 62 and partition walls 47 as the feed drawer laterally reciprocates over the mold box 40 and core assembly 42. The feed drawer 144 , is laterally reciprocated along a pair of rails 152 through two sets of pivoting crank arms, each set including a rotational arm 160 and a pivotal arm 162 one set being located on each side of the feed drawer 144 . The rotational arms 160 extend from a common axle 163 carrying a pair of chain driven sprockets 164 , only one of which is shown in the drawings . One of the sprockets 164 carries a chain 166 which is connected to a pivot arm 168. An. expandable bellows 170 is mounted between a stationary plate 172 and the pivot arm 168 . The bellows 170 is connected to the air accumulator 134 by a tube which includes a two-way safety valve 154 and a three-way control valve 156. Expansion of the bellows

170 causes the downward motion of the arm 168 and, through the chain 166, the counter-clockwise rotation of the sprockets 164 , as viewed in FIGURE 1. The other sprocket 164 carries a chain 167 which is connected to a pivot arm 169. A coil-spring

171 is mounted between the stationary plate 172 and the pivot arm 169 , whereby extension of the spring 171 causes the downward motion of the arm 169 and, through the chain 167 , the clo ckwise rotation of the sprockets 164 , as viewed in FIGURE 1. The chains 166 and 167 are wrapped around the sprockets 164 about 320° in opposing directions to rotate the axle 163 in opposing directions upon expansion of the bellows 170 and spring 171, respectively . As is the case with the pallet feed assembly 12, the feed drawer 144 is slowly accelerated and decelerated, with rapid interim motion, through the translation of ro tational motion to a reciprocating motion. Thus there are fewer shocks applied to newly formed green blocks . The vertically movable ram 142 is driven downwardly for compression by means of a plurality of air inflatable or extendible chambers 173 and returned to an upper or home position by extension of a plurality of resilient coil springs 175. Two stationary, horizontal platforms 177 and 179 are attached to the main frame 78 at spaced-apart locations above, and parallel to, the bed 24. Sixteen coil springs 175, substantially identical to the springs 110 of the spring assemblies 102, are vertically mounted upon the upper stationary plate 179, eight springs 175 along the front edge of the platform

179 and eight springs 175 along the rear edge of the platform 179. The springs 175 carry a unitary ram assembly 181 whereby extension of the springs 110 causes the ram assembly 181 to rise relative to the bed 24. The ram assembly 181 includes an upper frame 183 carried by the springs 11Q. Four legs 185 extend vertically downwardly from the frame 183 and are attached to the ram 142. A lower ram platform 187 is secured to the upper surface of the ram 142, parallel to the upper frame 183 and the bed 24. Eight elongated posts 189, threaded at. each end, extend vertically upwardly from the base plate- 187. A cylindrical spacer sleeve 190 is coaxially mounted upon each of the posts 189, extending through an aperture 192 defined in the lower stationary platform 177. An upper ram platform 194 is mounted upon the posts 189, resting upon the spacer sleeves

190. The posts 189 are threaded at each end for securing the platforms 187 and 194 in fixed spaced relation to one another with nuts 196. As noted hereinabove, the posts 189 and coaxial sleeves 190 extend through apertures 192 defined in the platform 177, thus, the platforms 187 and 194 move as a unit and totally independent of the platforms 177 and 179. The posts 189 located at the corners of the platforms 187 and 194 extend upwardly through apertures defined in the stationary platform 179. Stop members 195 are threaded onto the posts 189 to provide lower stop means for the ram assembly 181.

Three extendible chambers 173 are defined between the stationary platform 177 and the lower ram platform 187, and three extendible chambers 173 are defined between the stationary platform 179 and the upper ram platform 194. Each extendible chamber 173 includes a rigid base member 198, a rigid upper member 200 and a flexible, air-impermeable bellows member 202 sealingly secured around its periphery to the members 198 and 200. Each of the extendible chambers 173 is capable of providing 50,000 pounds (22.7 metric tons) of pressure at 100 p.s.i. (7 kg per square centimeter) air pressure. The bellows members 202 in the depicted embodiment are available from the Firestone Rubber Company under the designation 134.15 Airstroke Airmount.

A filler tube 204 connects each of the chambers 173 with a manifold 206. The manifold 206 is connected to the air accumulator 134 by two tubes 208 to ensure sufficient air flow, for example, six cubic feet (1.7 desistere) of air per second. Each of the tubes 208 includes a two-way safety valve 210 and a three-way control valve 212 for filling and exhausting air for the chambers 173. As desired, individual valve means may be provided within each of the filler tubes 204 for selecting the number of chambers for extension. Simultaneous vertical extension of the chambers 173, by the introduction of compressed air through, the tubes 208, causes the separation of the platforms 177 and 179 from the ram platforms 187 and 194, respectively. As a result, the ram frame assembly moves vertically downwardly, away from the stationary platforms 177 and 179. As the head 140 is carried by the tracks 146, this downward movement of the ram 142 pushes the head 140 into contact with the mix previously deposited into the mold box 40. The resistance of the mix lifts the head 140 off of the track 146 and into direct contact with the ram 142 as the ram descends. The springs 175 resist the expansion of the bags, but at a relatively insignificant level compared to the additive forces of the chambers 173. Consequently, employing the depicted embodiment of the present invention, forces of about 1,0.00 p.s.i. (70 kg per square centimeter) are applied to the blocks for compression. As desired, additional platforms may be added to the unitary ram assembly 181, provided the additional stationary platforms are added to the frame 78 with interconnecting bellows members to define additional chambers 173.

When the air is exhausted from the chambers through. the valves 212, the springs 175 extend between the platform 179 and the frame 183 to push the -frame 183 upwardly away from the platform 179. In this manner, the unitary ram assembly 181 is lifted from the head 140, which is then picked up by the track 146. The total vertical motion of the ram 142 is only about three inches (eight centimeters).

In operation, at the beginning of a block machine cycle, the chambers 173 are in a deflated condition and the springs 175 have pushed the unitary ram assembly 181 to an upper position. Suitable stop means are secured to the main frame 78 for engaging the ram assembly to prevent free upward motion. The chambers 80 and 83 are filled with- pressurized water, maintaining the cradle 50 in its uppermost position.

The cradle 50 supports the mold box 40 and continuously vibrating core assembly 42 about nine inches (23 cm) above the bed 24, clear of a newly formed block.

Rotation of the arm 34 causes the cart 26 to advance to the pallet magazine 20, where the arms 30 engage the uppermost pallet 22. Continued rotation of the arm 34 causes the cart 26 to reverse direction and the arms 30. to pull the uppermost pallet 22 off the pallet stack and into the channels 32. As a pallet 22 enters the channels 32, the preceding pallets 20 are advanced within the channels to discharge the pallet carrying the newly formed block and deposit an empty pallet 22 on the bed 24.

When an empty pallet 22 has been deposited upon the bed 24, the air valves 138 are vented to release the pressurized water in the chambers 80 and 83. The coil spring assemblies 102 extend to drive the cradle' 50 down. As the cradle 50 is lowered, the mold box 40 and core assembly 42 are deposited upon the empty pallet 22. The pallet 22 is squeezed between the bed 24 and mold box 40 by the spring assemblies 102, thus preventing any "chatter" from pallet vibration.

As the mold box 40 and core assembly 42 are lowered the mold box becomes disengaged from their mating engagement with the head 140, so that the head 140 is then free to travel laterally along the tracks 146. The head 140 is pushed along the roller tracks 146, through, the link arm 148 by the feed drawer 144, which has been previously loaded from a hopper 214. The bellows 170 is extended by opening the valve 156 to permit air flow from the accumulator 134. Expansion of the bellows 170 causes the arm 168 to pivot downwardly, pulling the chain 166 and rotating the axle 163 in a counter-clockwise direction. As the sprocket 163 rotates, the rotational arm 160 urges the pivotal arm 162 to the left, pushing the feed drawer 144 over the mold box 40. As the drawer 144, which is open at the bottom, slides over the mold box 40, the mix is deposited therein. Vibration of the core assembly 42 causes the mix to settle within the mold box 40 and around the core members 60. After the feed drawer has emptied its contents, the valve 156 is vented, releasing the air pressure within the bellows i70. The spring 171, which, was compressed between the pivot arm 169 and the plate 172 by the counter-clockwise rotation of the axle 163, is then free to extend. Extension of the spring 171 causes the clockwise rotation of the axle 163, returning the drawer 144 to a loading position directly under the hopper 214. As the drawer 144 returns, the link, arm 148 pulls the head 140 back into a compressing position directly over the mold box AQ. Horizontally adjustable stop means 216 are provided for ensuring correct positioning of the head 140 relative to the mold box 40.

When the head 140 has returned to a compressing position, as indicated through contact with a limit switch, for example, the chambers 173 are simultaneously expanded by the introduction of pressurized air from the accumulator 134 through the valves 210 and 212 at about 100 p.s.i. (7 kg per square centimeter) through the filler tubes 204. As the chambers 173 expand between the pairs of stationary platforms 177 and 179 and the ram platforms 187 and 194, respectively, the unitary ram assembly 181 is driven downwardly away from the platforms 177 and 179 with a force which is essentially the sum of the force applied by each of the extendible chambers 173. The ram 142 engages the head 140. which is in turn forced into compressing engagement with, the mix previously deposited within the mold box 40. When the ram 142 reaches the bottom of its downward stroke, as determined by engagement of the stop members 195 with the platform 179, and indicated by a limit switch, for example, the chambers 80 and 83 are expanded to strip the mold box 40 and core assembly 42 from the compressed block. Water is then forced into the chambers 80 and 83 by opening the valve 138 to pressurize the water tank 84. As the chambers 80 and 83 are filled, the cradle 50 is again raised, lifting the mold box 40 and core assembly 42. The head 140, under the force of the ram assembly 181 prevents the molded blocks from rising with the mold box 40 and core assembly 42. In consequence, the mold box 40 and cores 60 are stripped from the block and raised about nine inches (.23 cm) in mating relation to the head 140. At this point, the machine has returned to the initial point in the cycle and is prepared to make another set of blocks.

It will be recognized that suitable controls and limit switches as are recognized in the art may be applied to the presently described apparatus in order to provide sequential, automatic operation through a central controller.. Industrial Applicability:

Employing the method and apparatus of the present invention an improved block having greater strength, can be produced with reduced void volume resulting in reduced water and cement consumption. In addition, the apparatus operates at reduced noise levels, thus improving the work environment, and the apparatus has a low sensitivity to the dust and grit which frequently circulate in the block-making environment. The vibration of the core assembly, used for settling the mix within the mold box, is isolated from the mold box, the pallet and the head,, as well as the remainder of the apparatus, thus reducing the requirements for maintenance and parts replacement Moreover, the inflated chambers are not particularly sensitive to vibration. The disclosed system is fast because the distances of vertical travel by the stripping mechanism is limited to just slightly more than the height of the mold box and the compression mechanism travels only about three inches (7.8 cm). The compression system also permits the development of large compressive forces over a small area through, the summation of a plurality of expandable chambers operating upon a plurality of pairs of interrelated platforms. While a preferred embodiment of the present invention has been shown and described herein, it is understood that various changes and modifications may be made without deviating from the spirit or scope of the invention and there is no intention to limit the scope of the invention except as set forth in the following claims.

Claims

The Claims :

1. A system for making a block from masonry mix comprising a main frame, a pallet, a bed for a pallet on said main frame, said bed maintaining said pallet in a generally horizontal position, a mold box for defining the side walls of at least one block, said mold box being mounted upon a cradle which is supported on said main frame for vertical movement toward and away from said bed for depositing mix in said mold box, inflatable compressing means including a ram, means for supporting said compressing means on said frame for movement into and out of said mold box, and means for effecting a molding cycle which in sequence causes (a) said mold box to rest upon said pallet, (b) filling said mold box with, the desired amount of mix, (c) inflating said compressing means to compress said mix (d) raising said mold box from said pallet, and (el moving said ram away from said pallet.

2. The apparatus of Claim 1 wherein said cradle is supported on said main frame by an inflatable lift assembly whereby inflation of said lift assembly raises said mold box relative to said bed.

3. The apparatus of Claim 2 wherein said lift assembly comprises a primary chamber defined by a first plate, a second plate and an interconnecting bellows member and a secondary chamber defined by a first plate, a second plate and an interconnecting bellows member.

4. The apparatus of Claim 1 wherein said compressing means includes a compressing ram and a head, said head being carried by generally horizontal track means mounted upon said ram and having a shape adapted to fit within said mold box.

5. The apparatus of Claim 4 wherein said means for depositing mix in said mold box comprises a laterally reciprocating feed drawer and said head is interconnected with said feed drawer for horizontal reciprocating movement therewith.

6. The apparatus of Claim 2 wherein resilient means interconnect said cradle and said main frame to deflate said lift assembly.

7. The apparatus of Claim 1 wherein resilient means interconnecting said cradle and said main frame urge said mold box into contact with said pallet.

8. The apparatus of Claim 1 wherein said compressing means comprises an inflatable chamber defined by a first platform, a second platform spaced apart from said first platform and a flexible bellows members interconnecting said first platform and said second platform.

9. The apparatus of Claim 1 wherein said ram is pressurized by a plurality of extendible chambers defined by first member, including a plurality of spaced apart platform a second member, including a plurality of spaced apart platform each of said second member platforms overlying a first member platform, and a plurality of flexible bellows members each of said bellows members connecting a platform of said first member with the overlying platform of said second member.

10. The apparatus of Claim 1 and further comprising a core means mounted upon said cradle for movement with, said mold box.

11. The apparatus of Claim 10 wherein said core means includes means for vibrating said core means.