The present invention relates to concrete mixing apparatus and more particularly, to a mobile concrete mixing apparatus for mounting on a dump truck or trailer.
The prior art teaches a number of different truck-mounted mobile mixers. They have a number of shortcomings. The truck is dedicated to the mixer, that is, when the mixer is not needed, the truck cannot be used for anything else.
The boxes of the prior art mixers are V-shaped. They are wide at the top and taper downwardly towards the belt or auger for discharge. As a result, the trucks are top heavy with a high center of gravity, making them dangerous in the road.
The material transport mechanisms for moving the materials to the back of the truck for mixing, whether they are belts or augers, are long, typically stretching the entire length of the box, 16 to 18 feet. Because they are so long, everything associated with the material transport needs to be heavy duty, including the sprockets, chains, bearings, hydraulics, etc. They are subject to more wear and tear. It also means that the truck burns more fuel.
Belts and augers that extend the length of the box are more dangerous, increasing the chance of injury.
Because materials are being transported from farther away in the truck, the mixing is harder to start.
Augers and belts get stuck quite often, especially when the material has been sitting for a while. This is due, in part, to the sand being compacted at the bottom from the motion of the truck on the road during transport.
Manufactured sand is next to impossible to move using a long auger. It constantly gets stuck. This happens more often in very cold weather because any moisture in the sand freezes, somewhat solidifying the sand. Further, the V-shape at the bottom is more exposed to the elements and therefore freezes faster than the rest of the sand. The current solution is to spray the sand with calcium chloride, but this degrades the quality of the concrete. Another solution is to use electric heating rods, which consume a lot of energy and are not very efficient.
The present invention continuous mixer that can be installed in the bed of a standard dump truck in place of the truck's tailgate. The mixer uses the truck bed for some of the material to be mixed, such as sand and gravel. The mixer has a cement hopper for holding the cement, a pair of belts for moving the mixing materials from the truck bed, and a chute for mixing the cement and mixing materials with water and for depositing the mixture where desired.
The hopper stands generally upright in the truck bed when the bed is down and tilted at about 45° when the bed is tilted up. If the hopper is a narrower than the bed, optional spacers can be installed to fill the gap and prevent side-to-side movement of the mixer.
The hopper has a top hatch for filling the hopper with cement. The hatch cover is attached by hinges and optionally includes a gasket to keep moisture out.
The hopper has a hopper auger assembly at the bottom of the hopper that feeds cement to a hopper opening at the bottom center of the hopper. Gravity feeds the cement to the auger assembly. Optionally, the center of the hopper auger assembly is covered with a pipe to prevent the cement from flowing out of the hopper opening when the mixer is not in operation.
The pair of feed belts within a housing sit below the hopper. The left belt extends horizontally between an outer end below the hopper left side wall to an inner end at the hopper opening. The right belt extends horizontally between an outer end below the hopper right side wall to an inner end at the hopper opening. A gap separates the belts.
Each belt is a continuous band of robust, flexible material that loops around rollers. The bands have lateral cleats to help pull the material. The belts are oriented at an angle, typically about 90°, to the bottom of the hopper so that the belts are generally parallel to the ground during operation. The top of the belt housing is open to the truck bed and the mixing materials are pushed onto the belts by gravity. The belts feed the mixing materials to the gap where they fall to a feed opening in the bottom wall of the housing. Optionally, the amount of the mixing material reaching the gap is controlled by limiting gates in gate walls built like a pyramid over the gap.
Below the belt housing is a mixing chute. The chute has an elongated, U-shaped trough and a flat ceiling with a pivot end and a discharge end. The chute is mounted to pivot at the pivot end vertically between a storage position, where the discharge end of the chute is higher than the pivot end, and a discharge position, where the discharge end is at or lower than the pivot end. In the present design, a hydraulic piston moves the chute.
An inlet at the pivot end is vertically aligned with the feed opening. The hopper auger assembly feeds cement into the hopper opening where it falls into the feed opening, and the feed belts feed the mixing materials into the feed opening. These dry materials drop through the feed opening into the chute feed inlet.
A mixing auger extends through the trough and combines the dry materials and water to form the concrete as they travel the length of the chute to the discharge end. Water is added by a water inlet to the chute at a distance of about ¼ the length of the mixing auger from the pivot end to permit the dry materials to be mixed before the water is added.
The hopper auger assembly, feed belts, and mixing auger are driven by drive mechanisms. The hopper auger assembly and feed belts are driven by a motor that directly drives the feed belts and that drives a drive belt or chain to rotate the hopper auger assembly. The mixing auger is driven by a motor, preferably mounted at the discharge end of the chute.
Other objects of the present invention will become apparent in light of the following drawings and detailed description of the invention.
For a fuller understanding of the nature and object of the present invention, reference is made to the accompanying drawings, wherein:
The present invention, shown in
The mixer 10 uses the truck bed 3 for some of the material 5, 6 to be mixed. For example, when making concrete, the truck bed 3 holds sand 5 and gravel 6, as shown in
In the present specification, the directions “left” and “right” are used as viewed from the back of the truck 2. The terms “front” and “back” are relative to the back of the truck 2. In other words, when looking at the mixer 10 from the back of the truck 2, the front is closest to the viewer.
The mixer 10 has a cement hopper 12 for holding the cement 4, a pair of belts 14, 16 for moving the mixing materials 5, 6 from the truck bed 3, and a chute 18 in which the cement 4 and mixing materials 5, 6 are mixed with water by an auger 150 and for depositing the concrete mixture 7 where desired.
Because cement 4 is adversely affected by moisture, the cement hopper 12 is enclosed to keep most moisture out for at least the amount of time that the cement 4 will be in the hopper 12 prior to mixing.
As shown in
As shown in
In general, the width (side to side) of the hopper 12 is a bit narrower than the width of the truck bed 3 so that it is relatively easy to mount and dismount without needing perfect alignment. The sides of the truck bed 3 are used to prevent side-to-side movement of the mixer 10 when installed in the bed 3. If the hopper 12 is narrower than the truck bed 3, optional spacers 286, shown in
The manner by which the mixer 10 is mounted in the truck bed 3 is described below.
As shown in
As shown in
In the first configuration of the hopper auger assembly 60 with separate, coaxial shafts 63, the shafts 63 can be rotated independently of each other. One advantage to this arrangement is that the two augers 61, 62 can be rotated at different speeds if desired. Another advantage is that the two augers 61, 62 can be identical, that is, with the same clockwise or counterclockwise twist, but rotated in opposite directions to move the cement 4 to the hopper opening 65. Since they are identical, only one tool or mold is needed to make both augers 61, 62. The disadvantage to two independent augers 61, 62 is that a more complex mechanism is needed to mount and rotate the augers 61, 62 independently.
In the second configuration of the hopper auger assembly 60, shown in
In the present design, the shaft 63 has a diameter of 2 to 3 inches, and the blades 64 have a height of 1 to 2 inches, for a total diameter in the range of 4 to 7 inches. The blades 64 have a pitch of about 35°. These dimensions are merely illustrative and can differ for a particular application.
Optionally, to prevent the cement 4 from flowing out of the hopper opening 65 when the mixer 10 is not in operation, the center of the hopper auger assembly 60 is covered with a pipe 190 that fits over the auger assembly 60, as in
Optionally, there is a second blade pitching in the same direction of the main blade 64 for the length of the pipe 190. The two blades prevent the cement 4 from flowing through the pipe 190 when the mixer 10 is not in operation. Optionally, a rubber plug can be installed in the hopper opening 65 to prevent spillage during transportation.
Optionally, one or more vibrators 272 are mounted to the outside of the hopper 12, as shown in
A tube 66 extends between the pipe opening 194 and the hopper opening 65 to guide the cement 4 to the hopper opening 65. Typically, the openings 65, 194 and tube 66 are rectangular or round with a cross-sectional area between 28 (6″ round) and 30 (5″×6″) square inches. In the present design, the tube 66 is about 6 inches long.
Below the hopper 12 is the pair of linearly aligned 14, 16 within a belt housing 67. As shown in
Each belt 14, 16 has a continuous band 90 of robust, flexible material that loops around an inner roller 92 and an outer roller 94.
In one configuration, the bands 90 are composed of vulcanized rubber with 3 or more plies. The bands 90 have lateral cleats 96 to help the bands 90 pull the material 5, 6. In the present design, the cleats 96 are 1 to 1½ inches high and 6 to 8 inches apart.
As shown in
In another configuration, shown in
Optional support rollers 95, shown in
In another configuration, not shown, the bands 90 are composed of metal chains that drag the materials. The chain has teeth to help the bands 90 pull the materials 5, 6. The chains ride on metal plates between the rollers 92, 94 for support.
The belts 14, 16 are oriented at an angle downwardly, typically about 90°±15°, from the bottom wall 36, as shown in
The belts 14, 16 are sized as required for the particular application. In the present design, each belt 14, 16 is 35 inches long and 10 inches wide. The rollers 92, 94 are 4 to 5 inches in diameter and spaced approximately 30 inches center-to-center.
The top of the belt housing 67 is open to the truck bed 3, as at 72. The mixing materials 5, 6 are pushed by gravity to the upper section 98 of the belts 14, 16. When the belts 14, 16 are in operation, they feed the mixing materials 5, 6 to the gap 86, where they fall to a feed opening 102 in the bottom wall 74 of the housing 67.
Optionally, the amount of the mixing materials 5, 6 reaching the gap 86 is controlled by limiting gates 202, shown in
Each gate 202 includes a door 210 that slides vertically within grooves 212 on the inside of an opening 214 in the gate wall 203. How far the door 210 is open controls the amount of mixing materials 5, 6 that reach the gap 86.
The door 210 is controlled by a gate control mechanism 216. In the present design, shown in
The belt housing 67 includes an optional mechanism for emptying the compartments 24, 26 without mixing the materials 5, 6, shown in
As mentioned above, when mixing concrete, both sand 5 and gravel 6 are mixed with the cement 4, and when mixing gunite, only sand 5 is mixed with the cement 4. When mixing concrete, the truck bed 3 has a barrier 22 that extends front to back through the center and divides the bed 3 into two compartments 24, 26, as shown in
A tube 104 extends between the gap 86 and the feed opening 102 to guide the mixing materials 5, 6 to the feed opening 102. Typically, the opening 102 and tube 104 are rectangular or round with a cross-sectional area between 78 (10″ round) and 100 (10″×10″) square inches. In the present design, the tube 104 is about 6 inches long.
Attached to the belt housing 67 below the feed opening 102 is the pivot end 128 of a mixing chute 18. The chute 18, shown in
The chute 18 is mounted, as at 130, to pivot vertically at a pivot end 128 between a storage position 110, shown in
As previously described, the chute 18 pivots vertically between the storage position 110, the discharge position 112, and the maximum position 114. In the present design, the mechanism 180 for lifting and lowering the chute 18 includes a hydraulic piston 182. As shown in
In the storage position 110, the discharge end 144 is substantially higher than the pivot end 128 so that gravity prevents materials from exiting through the discharge end 144. Typically, for travel, the chute 18 will be generally parallel to the front wall 32, as in
In the discharge position 112, the discharge end 144 is at or below the pivot end 128. The typical discharge position 112 is where the chute 18 is at about 45°-50° to the front wall 32, as in
The maximum position 114 is the maximum angle of the chute 18 to the front wall 32. Typically, this will be about 90°, as shown in
An inlet 146 in the chute ceiling 120 at the pivot end 128 is vertically aligned with the feed opening 102. As described above, the hopper auger assembly 60 feeds cement 4 into the hopper opening 65 where it falls into the feed belt gap 86 and into the feed opening 102, and the feed belts 14, 16 feed the mixing materials 5, 6 into the feed opening 102 in the belt housing 67. These dry materials, the cement 4 and mixing materials 5, 6, drop through the feed opening 102 into the chute feed inlet 146.
A mixing auger 150 extends through the trough 116 of the chute 18 for the length of the chute 18. The mixing auger 150 combines the dry materials and water to form the concrete 7 as they travel the length of the chute 18 from the chute feed inlet 146 to the discharge end 144, where the concrete mixture exits an opening 148 in the discharge end 144.
In the present design, the mixing auger shaft 152 has a diameter of 2½ inches, and the blade 154 has a height of 3-½ to 5 inches, for a total diameter of 9-½ to 12-½ inches. The peak-to-peak distance of the blades 64 is 9 to 10 inches and the blades 64 have a pitch of about 30°.
Water is added to the chute 18 at a distance of about ¼ the length of the mixing auger 150 from the pivot end 128. This permits the dry materials to be mixed before the water is added. The remainder of the ¾ of the mixing auger 150 mixes the dry materials and water together for proper hydration of the concrete 7. As shown in
The hopper auger assembly 60 and feed belts 14, 16 are driven by a drive mechanism 170, a typical configuration of which is shown in
The mixing auger 150 is driven by a hydraulic motor 156, preferably mounted at the discharge end 144 of the chute 18.
The mixer 10 is mounted in the truck bed 3 and is generally attached in the same manner as a tailgate. Optionally, the mixer 10 has hooks or eyelets at the top so that the mixer 10 can lifted by crane or other lifting machine. The upper attachment is shown in
The other side 258 of the bed bracket 246 has a cylindrical spacer 260 extending perpendicularly from the side of the hopper 12. The spacer 260 aligns with the hole 8 in the truck bed wall 9 that normally holds the tailgate. A pin 262 extends through the bed hole 8 and the spacer 260 and is secured by a hairpin cotter pin 264 or the like through a radial hole 264 in the pin 262. Optionally, the spacer 260 is swappable so that spacers 260 of the appropriate length for the hopper/truck bed wall gap 284 can be used.
For the lower attachment, pins or flat bars 270 are welded horizontally to the feed belt housing back wall 68 so that they extend outwardly from the end walls 76, as seen in
Thus, it has been shown and described a mobile continuous mixing apparatus. Since certain changes may be made in the present disclosure without departing from the scope of the present invention, it is intended that all matter described in the foregoing specification and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.
Filing Document | Filing Date | Country | Kind |
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PCT/US2021/070699 | 6/11/2021 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2021/253052 | 12/16/2021 | WO | A |
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