JP7584971B2 - Material mixing device and material mixing method - Google Patents

Description

The present invention relates to a dosing device, a material mixing device, and a material dosing method.

Conventionally, a mixed soil preparation device and a mixed soil preparation method are known in which multiple materials are loaded onto a belt conveyor, and these multiple materials are mixed while being transported by the belt conveyor to obtain mixed soil (see, for example, Patent Document 1).

JP 2011-156735 A

Water may be supplied to the multiple materials taking into consideration their mixing ratio and the moisture content of the final mixed soil, and the mixed soil preparation device disclosed in Patent Document 1 is also equipped with a water supply unit. The water supply unit in the mixed soil preparation device disclosed in Patent Document 1 supplies water toward the belt conveyor in order to avoid unevenness in the mixed soil caused by bentonite, one of the mixed materials, becoming globular. However, in the mixed soil preparation device of Patent Document 1, the surface of the belt conveyor may get wet, causing bentonite and other materials to adhere to the belt conveyor. The materials that adhere to the surface of the belt conveyor are not mixed into the mixed soil. For this reason, it is expected that the final mixed soil will not have the desired mixing ratio, the moisture content will not be the desired value, the materials will not be mixed homogeneously, and so on.

Therefore, the present invention aims to obtain a soil mixture with the desired mixture state.

The material mixing device disclosed in the present specification includes a plurality of material input sections that input a plurality of materials used to prepare mixed soil, the plurality of materials including a material made of bentonite and at least two or more materials including sand and gravel; an upstream conveyor that transports the plurality of materials input by the material input sections; a downstream conveyor arranged downstream of the upstream conveyor; a first water supply section that supplies moisture to the plurality of materials from the material input section before they reach the material loading surface of the upstream conveyor; and a transfer chute that is provided at a transfer section between the upstream conveyor and the downstream conveyor and has a collision surface that causes the plurality of materials discharged from the upstream conveyor to collide with each other and drop onto the downstream conveyor. The material input section into which a harder material is input is provided downstream of the upstream conveyor, and the transfer chute causes the at least two or more materials transported on the upstream conveyor to collide with the collision surface, thereby varying the rebound distance according to the hardness of the at least two or more materials.

The material mixing device disclosed in this specification includes the above-mentioned feeding device, an upstream conveyor that transports a plurality of materials including the material fed by the feeding device, a downstream conveyor arranged downstream of the upstream conveyor, and a transfer chute provided at the transfer section between the upstream conveyor and the downstream conveyor, the transfer chute facing the downstream end of the upstream conveyor has a collision surface with which the plurality of materials discharged from the downstream end collide and drop onto the downstream conveyor, the collision surface being concavely curved.

Another material mixing device disclosed in this specification includes a moisture content measuring unit that measures the actual moisture content of a mixed material in which multiple materials are mixed and transported on a conveyor, a water supply unit that supplies water to the mixed material that falls downstream of the conveyor toward a pile of the mixed soil, and a control unit that calculates the amount of water to be supplied to the mixed material so that the moisture content of the mixed material reaches the target moisture content based on the actual moisture content and a preset target moisture content of the mixed material, and causes the water supply unit to supply the mixed material with the amount of water to be supplied.

Furthermore, the material input method disclosed in this specification is a method for inputting materials onto a conveyor in the preparation of mixed soil, and when the materials are input onto the material loading surface of the conveyor through a material input section, moisture is supplied to the materials before they reach the material loading surface.

According to the present invention, it is possible to obtain a soil mixture with the desired mixture state.

FIG. 1 is an explanatory diagram showing a schematic configuration of a material mixing device according to a first embodiment. FIG. 2 is an explanatory diagram showing the first conveyor and its periphery as viewed from above. FIG. 3 is an explanatory diagram showing an enlarged view of the second input device. FIG. 4 is a perspective view of a transfer chute installed at a transfer section of a conveyor. FIG. 5 is an explanatory diagram showing a schematic view of a state in which material that collides with the transfer chute rebounds in the first embodiment. FIG. 6 is a conceptual diagram showing the rebound distance of material that hits the transfer chute. FIG. 7 is an explanatory diagram showing the radius of curvature of the collision surface of the transfer chute provided in the material mixing apparatus of the first embodiment. FIG. 8 is a perspective view of a discharge chute provided in the material mixing apparatus of the first embodiment. FIG. 9 is a flow chart showing an example of control of the material mixing apparatus of the first embodiment. FIG. 10 is an explanatory diagram showing a typical state in which a material that collides with a transfer chute installed on conveyors arranged to cross each other rebounds. Figures 11(A) and 11(B) are schematic diagrams showing the rebound of material that collides with the transfer chute of the comparative example, where Figure 11(A) is a diagram viewed from the side of the first conveyor and the upstream side of the second conveyor, and Figure 11(B) is a diagram viewed from above the first conveyor and the second conveyor. FIG. 12 is an explanatory diagram showing the radius of curvature of the collision surface of a transfer chute installed at a transfer section of conveyors arranged to cross each other. FIG. 13(A) is a diagram showing a modified example of the second insertion device, and FIG. 13(B) is an explanatory diagram showing the state of the enclosure installed on the first conveyor as viewed from the downstream side of the first conveyor. FIG. 14 is an explanatory diagram showing a schematic configuration of a material mixing apparatus according to the second embodiment. FIG. 15 is an explanatory diagram of the crushing and mixing section provided in the material mixing apparatus of the second embodiment.

Below, the embodiments will be described with reference to the drawings. Note that the dimensions and ratios of each part in the drawings may not be illustrated to be exactly the same as the actual ones. Also, some details may be omitted in the drawings.

First Embodiment
First, a material mixing apparatus (hereinafter, simply referred to as a "mixing apparatus") 100 according to a first embodiment will be described with reference to Fig. 1. The mixing apparatus 100 according to this embodiment mixes sand S, bentonite B, which is a powder, and gravel G to prepare mixed soil M. The mixing apparatus 100 includes a first conveyor 1 having a material loading surface 1a, a second conveyor 2 having a material loading surface 2a, and a third conveyor 3 having a material loading surface 3a.

The first conveyor 1, the second conveyor 2, and the third conveyor 3 are arranged in this order from the upstream side. Therefore, in the relationship between the first conveyor 1 and the second conveyor 2, the first conveyor 1 is the upstream conveyor, and the second conveyor 2 is the downstream conveyor. In addition, in the relationship between the second conveyor 2 and the third conveyor 3, the second conveyor 2 is the upstream conveyor, and the third conveyor 3 is the downstream conveyor.

The mixing device 100 of this embodiment is equipped with three conveyors, but the number of conveyors is not limited to this, and the mixing device may be equipped with at least two conveyors.

In this embodiment, multiple conveyors are connected in series and arranged so that the conveying direction faces in one direction.

The mixer 100 is equipped with a feeder for each material to be mixed. The mixer 100 is equipped with a first feeder 10 for feeding sand S, a second feeder 15 for feeding bentonite B, and a third feeder 20 for feeding gravel G.

The first input device 10, the second input device 15, and the third input device 20 are provided in this order from the upstream side. The first input device 10, the second input device 15, and the third input device 20 all input material onto the material loading surface 1a of the first conveyor 1.

The first input device 10 is equipped with a hopper 10a and a feeder 10b as material input sections. The feeder 10b is a belt feeder, but may be another type of feeder (e.g., a screw feeder). Referring to FIG. 2 showing the first conveyor 1 and its periphery viewed from above, the hopper 10a is installed at a position shifted to the side of the first conveyor 1. Above the hopper 10a, a water supply nozzle 11 is provided as a first water supply section that supplies water to the sand S in the hopper 10a. The water supply nozzle 11 may be provided to supply water to the sand S cut out by the feeder 10b. The water supply nozzle 11 may also be provided to supply water to both the sand S in the hopper 10a and the sand S on the feeder 10b. In short, the water supply nozzle 11 may be provided so as to supply water to the sand S before it reaches the material mounting surface 1a of the first conveyor 1. As shown in FIG. 1, the water supply nozzle 11 is connected to the water tank 5 via a water supply line 12. A flow meter 12a and a water supply pump 12b are disposed in the water supply line 12. The flow meter 12a and the water supply pump 12b are electrically connected to the control unit 6, and the amount of water supplied through the water supply nozzle 11 is managed by the control unit 6. The amount of water supply is appropriately set taking into consideration the properties of the sand S and the properties of other materials to be mixed. Depending on the original water content of the sand S, the water supply may be stopped.

The control unit 6 is a computer and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and a storage unit that stores a control program. The control unit 6 is connected to an input interface. Here, the control program includes a drive control program for the water supply pump 12b. In this embodiment, the storage unit is a HDD (Hard Disk Drive), but it may be a SSD (Solid State Drive) or a portable storage medium read by a portable storage medium drive. The worker inputs a value of the water supply amount according to the properties of the sand S to the control unit 6 via the input interface. The control unit 6 drives the water supply pump according to the drive control program. The control unit 6 also controls the drive of the water supply pumps 18b, 22b, and 26b, which will be described later, in a similar manner.

The second input device 15 includes a hopper 15a and a feeder 15b as material input sections. The feeder 15b is a screw feeder, but may be another type of feeder (e.g., a belt feeder). A humidifier 15c is provided below the feeder 15b. As shown in FIG. 2, the humidifier 15c is installed above the material loading surface 1a of the first conveyor 1. However, as shown in FIG. 1, the humidifier 15c is installed so as not to come into contact with the material loading surface 1a. Referring to FIG. 3, the feeder 15b and a water supply nozzle 17 are attached to the humidifier 15c. A stirring blade 15c1 is attached inside the humidifier 15c. A drop port 15c2 is provided at the bottom of the humidifier 15c. The water supply nozzle 17 corresponds to the first water supply device and sprays mist-like moisture into the humidifier 15c. Bentonite B supplied to the humidifier 15c absorbs moisture, is appropriately mixed by the mixing blades 15c1, and then is dropped from the drop port 15c2 onto the material mounting surface 1a. By humidifying the bentonite B in the humidifier 15c, it is possible to absorb moisture evenly without forming balls. In addition, because bentonite B is supplied to the humidifier 15c and has absorbed moisture appropriately when it is dropped from the drop port 15c2, it is less likely to turn into dust.

As shown in FIG. 1, the water supply nozzle 17 is connected to the water tank 5 via a water supply path 18. A flow meter 18a and a water supply pump 18b are disposed in the water supply path 18. The flow meter 18a and the water supply pump 18b are electrically connected to the control unit 6, and the amount of water supplied through the water supply nozzle 17 is managed by the control unit 6. The amount of water supply is appropriately set taking into consideration the properties of the bentonite B and the properties of the other materials to be mixed. The operator inputs the amount of water supply according to the properties of the bentonite B, etc., to the control unit 6 via the input interface. The control unit 6 drives the water supply pump 18b according to the input value of the amount of water supply.

The third input device 20 includes a hopper 20a and a feeder 20b as material input sections. The feeder 20b is a belt feeder, but may be another type of feeder (e.g., a screw feeder). Referring to FIG. 2, the hopper 20a is installed at a position shifted to the side of the first conveyor 1, similar to the hopper 10a. Above the hopper 20a, a water supply nozzle 21 is provided as a first water supply section that supplies water to the gravel G in the hopper 20a. The water supply nozzle 21 may be provided to supply water to the gravel G cut out by the feeder 20b. The water supply nozzle 21 may also be provided to supply water to both the gravel G in the hopper 20a and the gravel G on the feeder 20b. As shown in FIG. 1, the water supply nozzle 21 is connected to the water tank 5 via a water supply path 22. A flow meter 22a and a water supply pump 22b are provided in the water supply path 22. The control of the water supply pump 22b by the control unit 6 is the same as the control of the water supply pump 12b, so a description of it will be omitted here.

The water supply nozzle 11 supplies moisture to at least one of the sand S in the hopper 10a and the sand S on the feeder 10b. The water supply nozzle 17 supplies mist-like moisture into the humidifier 15c. The water supply nozzle 21 supplies moisture to at least one of the gravel G in the hopper 20a and the gravel G on the feeder 20b. Both water supply nozzles avoid supplying water directly to the first conveyor 1.

In this way, by avoiding the direct supply of water to the first conveyor 1, the first conveyor 1 does not become excessively wet, and the material is prevented from adhering to the first conveyor 1. This allows the first conveyor 1 to operate appropriately, and the mixing ratio of the materials in the mixed soil M can be set to a predetermined desired mixing ratio.

The material of the mixed soil M can be selected appropriately, and an injection device is prepared for each material. The mixed soil M may be made of raw soil such as construction waste soil, or additives. The additives include lime-based solidification materials such as quicklime and hydrated lime, cement-based solidification materials such as ordinary cement and blast furnace cement, soil improvement materials made of polymer materials, natural fibers, and chemical fibers made of resin, and are injected in the desired ratio to the other materials. This allows the properties and strength of the mixed soil M to be adjusted.

The mixing device 100 is equipped with a first transfer chute 30a, a second transfer chute 30b, and a discharge chute 35. The first transfer chute 30a is provided at the transfer section from the first conveyor 1 to the second conveyor 2, and is arranged to face the downstream end 1b of the first conveyor 1. The second transfer chute 30b is provided at the transfer section from the second conveyor 2 to the third conveyor 3, and is arranged to face the downstream end 2b of the second conveyor 2. The discharge chute 35 is provided downstream of the downstream end of the third conveyor 3, and is arranged to face the downstream end 3b of the third conveyor 3. The first transfer chute 30a and the second transfer chute 30b are common. The mixed material transported on the material loading surface 1a of the first conveyor 1 and discharged from the downstream end of the first conveyor 1 collides with the first transfer chute 30a and falls onto the material loading surface 2a of the second conveyor 2. The mixed material transported on the material loading surface 2a of the second conveyor 2 and discharged from the downstream end of the second conveyor 2 collides with the second transfer chute 30b and falls onto the material loading surface 3a of the third conveyor 3. The mixed material transported on the material loading surface 3a of the third conveyor 3 is then discharged from the third conveyor 3. The discharged material collides with the discharge chute 35 and is deposited in the accumulation area D.

In this embodiment, the order in which the feeding devices are installed is determined taking into consideration the properties of the materials fed from each feeding device and ensuring that these materials are mixed appropriately. Here, the feeding order of the materials will be explained, along with the material mixing action of the first transfer chute 30a, with reference to Figures 4 to 7.

First, referring to FIG. 4, the first transfer chute 30a has a frame 31 with one side open and upright walls on the other three sides. Referring to FIG. 5, the first transfer chute 30a is installed in a position downstream of the downstream end 1b of the first conveyor 1 and above the second conveyor 2, with the open side of the frame 31 aligned with the upstream side of the material conveying direction. A collision plate 32 is provided inside the frame 31. The collision plate 32 has a collision surface 32a. The collision surface 32a faces the downstream end 1b of the first conveyor 1. The collision surface 32a causes the sand S, bentonite B, and gravel G discharged from the downstream end 1b of the first conveyor 1 to collide with each other and fall onto the second conveyor 2. The collision surface 32a is curved in a concave shape. The horizontal cross section of the curved collision surface 32a is arc-shaped. Also, referring to FIG. 4, three shear bars 33 are provided at a position facing the collision surface 32a. The shear bars 33 promote mixing of the materials by colliding with the materials discharged from the first conveyor 1. The materials may collide with the shear bars 33 and fall before reaching the collision surface 32a, or may reach the collision surface 32a after contacting the shear bars 33. The materials that collide with the shear bars 33 bounce irregularly and the bouncing distance changes. As a result, the materials are dispersed and fall onto the material loading surface 2a of the second conveyor 2. The number of shear bars 33 may be other than three. The shear bars 33 are omitted in FIG. 5.

Now, referring to FIG. 6, sand S is fed into the first conveyor 1 at the most upstream side, and bentonite B is fed downstream of the feeding position of sand S. Then, gravel G is fed downstream of the position where bentonite B was fed. Therefore, sand S is first laid out in layers on the material loading surface 1a of the first conveyor 1, and bentonite B is fed on top of the sand S. Then, gravel G is fed on top of that. As a result, bentonite B is sandwiched between sand S and gravel G. In addition, bentonite B is appropriately watered and in a hygroscopic state, and sand S and gravel G also have an appropriate moisture content. Therefore, bentonite B clings to and adheres to the surface of each grain of sand S and each grain of gravel G, and is in a state where it is as if it is coating each grain of sand S and each grain of gravel G, and is difficult to separate from sand S and gravel G.

When the sand S, bentonite B, and gravel G in this state are released from the downstream end 1b of the first conveyor 1, each material collides with the collision surface 32a of the first transfer chute 30a. Each material that collides with the collision surface 32a of the first transfer chute 30a bounces back. The rebound distance of each material varies depending on its hardness. In other words, the speed of an object after bouncing back theoretically depends only on the rebound coefficient, and since the rebound coefficient is correlated with the hardness of the object, the harder the object, the higher the speed after bouncing back and the longer the rebound distance.

Here, the rebound distance of sand S is represented as L1, and the rebound distance of gravel G is represented as L2. Generally, gravel G particles are harder than sand S particles, so the rebound distance of gravel G particles is longer than that of sand S particles, and the relationship L1 < L2 holds. Note that bentonite B is not included in the comparison of rebound distances because it is attached to sand S and gravel G, and the comparison of rebound distances is made only between sand S and gravel G. Also, to make it easier to compare the rebound distances, the case of collision with shear bar 33 is not taken into consideration.

Because the relationship L1 < L2 holds between distance L1 and distance L2, most of the gravel G falls upstream of most of the sand S on the material loading surface 2a of the second conveyor 2. For this reason, gravel G is first spread out on the material loading surface 2a of the second conveyor 2, and sand S is supplied on top of that. In this way, by colliding with the transfer chute and causing the material to fall, the layers of material are subjected to an action of switching between the top and bottom. The material is mixed by being subjected to an action of switching between the top and bottom.

Furthermore, each material that collides with the collision surface 32a as shown by arrow 7a in FIG. 5 bounces off and falls toward the center of the width direction of the material loading surface 2a of the second conveyor 2 as shown by arrow 7b. The materials are mixed as they fall. As the materials fall, they may collide with each other, which further promotes mixing. If the collision surface 32a were flat, the colliding materials may be bounced off toward the outside of the conveyor, but by making the collision surface 32a curved as in this embodiment, the materials are prevented from bouncing off toward the outside of the conveyor.

Now, referring to Figure 7, the radius of curvature R of the curved collision surface 32a will be described. The radius of curvature R of the collision surface 32a is set in the range of 0.3W to 1.1W, where W is the total belt width of the first conveyor 1. For example, if the total belt width W is 500mm, the radius of curvature R is set in the range of 150mm to 550mm.

If the radius of curvature R is less than 0.3 times, which is the lower limit, it becomes difficult to provide the collision surface 32a so as to cover the entire belt width W of the first conveyor 1, and there is a possibility that material will be discharged from the first conveyor 1 toward the outside of the collision surface 32a. On the other hand, if the radius of curvature R exceeds 1.1 times, which is the upper limit, the collision surface 32a approaches a flat surface, making it difficult to obtain the effect of making it a curved surface. In addition, if the radius of curvature R exceeds 1.1 times, there is a concern that the frame 31 supporting the collision plate 32 will become larger and heavier. Therefore, it is desirable to set the radius of curvature R of the collision surface 32a to a length that is 0.3 to 1.1 times the entire belt width W. In addition, in order to fully obtain the effect of curving the collision surface 32a, it is more desirable to set the radius of curvature R to a length that is 0.5 to 0.6 times the entire belt width W.

The second transfer chute 30b has the same configuration as the first transfer chute 30a, and the same mixing action can be obtained in the second transfer chute 30b. In this way, in the mixer 100 of this embodiment, the material can be mixed each time it passes through the transfer section of the conveyor equipped with the transfer chute.

The conveying speed of each conveyor will now be explained. The conveying speed of conveyors used to prepare mixed soil is generally around 50 to 80 m/min. In contrast, each conveyor in this embodiment operates at a speed of, for example, 120 to 160 m/min. By operating each conveyor at high speed in this way, momentum is imparted to the material that collides with the curved collision surface 32a of the first transfer chute 30a or the second transfer chute 30b, further promoting the mixing of the rebounded material.

Next, the discharge chute 35 arranged downstream of the third conveyor 3, which is the last stage of the multiple conveyors, will be described with reference to FIG. 8. The discharge chute 35 is equipped with a collision plate 37 in a frame 36 with an open upstream side. The collision plate 37 faces the downstream end 3b of the third conveyor 3, and the collision surface 37a against which the mixed material collides is curved concavely. Unlike the collision surface 32a in the first transfer chute 30a and the second transfer chute 30b, the vertical cross section of the curved collision surface 37a is a quarter-circular arc. The collision surface 37a bounces the collided material downward and converts the horizontal velocity component of the material into a vertical component. As a result, there is little difference in the horizontal movement distance of the bounced material, and there is little variation in the falling point of the material, so each material falls in a close position. For this reason, the mixed material is difficult to separate and is easy to accumulate on the ground surface while maintaining the mixed state. It should be noted that a chute with a collision surface of this shape can also be used as a transfer chute. For example, when the material falls a long distance at the transfer section of the conveyor, a chute with a collision surface shaped like collision surface 37a can be used as a transfer chute. A collision surface of this shape makes it easier for the material to bounce downward, and can reduce the ratio of horizontal movement to the fall distance. If the ratio of horizontal movement to the fall distance of the bounced material is small, the horizontal movement distance of the material can be shortened even if the material falls a long distance.

Returning to FIG. 1, the mixing device 100 is equipped with a water supply nozzle 25 as a second water supply unit and a continuous moisture meter 27 as a moisture content measuring unit. The water supply nozzle 25 is provided below the discharge chute 35. As a result, the water supply nozzle 25 supplies water to the mixed material that collides with the discharge chute 35 and falls. The mixed material to which water has been supplied is piled up in the accumulation area D as the final mixed soil M. The water supply nozzle 25 is connected to the water tank 5 via a water supply path 26. A flow meter 26a and a water supply pump 26b are arranged in the water supply path 26. The flow meter 26a, the water supply pump 26b, and the continuous moisture meter 27 are electrically connected to the control unit 6, and the amount of water supplied through the water supply nozzle 25 is managed by the control unit 6.

Here, the continuous moisture meter 27 measures the actual moisture content of the mixed material being transported on the material loading surface 3a of the third conveyor 3. The continuous moisture meter 27 in this embodiment is a near-infrared continuous moisture meter, but any conventionally known type of continuous moisture meter can be used. For example, a neutron continuous moisture meter can be used. These continuous moisture meters are conventionally known, so detailed descriptions thereof are omitted. By supplying water that reflects the measurement results of the continuous moisture meter 27, the actual moisture content of the mixed soil M can be adjusted to approach the target moisture content. Specifically, the control unit 6 operates the water supply pump 26b to compensate for the difference between the actual moisture content of the mixed material measured by the continuous moisture meter 27 and the preset target moisture content, and supplies water from the water supply nozzle 25 to the mixed material.

In this embodiment, water is supplied to the sand S from the water supply nozzle 11, and to the gravel G from the water supply nozzle 21. Here, since the sand S and gravel G have a relatively large grain size and good drainage properties, even if the amount of water supplied from the water supply nozzle 11 or the water supply nozzle 21 increases, the excess water flows away. For this reason, the sand S and gravel G are unlikely to have excess moisture, and it is rare for the actual moisture content of the mixed material to be greater than the target moisture content of the final mixed soil M. For this reason, the target moisture content of the final mixed soil M can be adjusted by supplying water from the water supply nozzle 25.

Here, an example of control in the mixing device 100 will be described with reference to FIG. 9. First, in step S1, the control unit 6 reads the target moisture content value input in advance. The target moisture content is input to the control unit 6 by the operator via the input interface. In step S2, the control unit 6 reads the measured value of the actual moisture content measured by the continuous moisture meter 27. In step S3, the control unit 6 calculates the water supply amount based on the target moisture content value read in step S1 and the actual moisture content value read in step S2. The water supply amount is calculated as the difference between the target moisture content value and the actual moisture content value. In step S4, the control unit 6 determines the rotation speed of the water supply pump 26b based on the water supply amount calculated in step S3. Then, in step S5, the control unit 6 issues a drive command to the water supply pump 26b to drive the water supply pump 26b at the rotation speed determined in step S4. In step S6, which follows step S5, the control unit 6 determines whether a predetermined time has elapsed. When the control unit 6 makes a positive judgment (Yes judgment) in step S6, it repeats the process from step S2 to step S6. On the other hand, when the control unit 6 makes a negative judgment (No judgment) in step S6, it repeats step S6 until a predetermined time has elapsed and a positive judgment is made in step S6. Here, the predetermined time in step S6 can be set arbitrarily, for example, to 1 to 2 seconds. The lower limit of the predetermined time in step S6 is about 0.3 seconds, and the upper limit is about 10 seconds. The reason why the lower limit is about 0.3 seconds is that even if the process from step S2 to step S6 is repeated at intervals of less than 0.3 seconds, the amount of data and the amount of calculation will increase, and this will not lead to further improvement in the accuracy of the control of the moisture content of the mixed soil M. The reason why the upper limit is about 10 seconds is that if the process from step S2 to step S6 is repeated at intervals of 10 seconds or more, accurate sampling will not be possible and the variation in moisture content will increase.

The mixed material receives water from the water supply nozzle 25, and the moisture content is adjusted, and the final mixed soil M is piled up in the accumulation area D.

(First Modification)
Next, referring to Figures 10 to 12, a modified example will be described in which the conveyors are arranged to cross each other so that the conveying direction changes at the transfer section between the upstream conveyor and the downstream conveyor. Figures 10 to 12 show an example in which the first conveyor 1 and the second conveyor 2 are arranged to cross each other, but the same applies to the case in which the second conveyor 2 and the third conveyor 3 are arranged to cross each other.

In the first modified example, as shown in FIG. 10, a first transfer chute 30a with a curved collision surface 32a is used to prevent separation of the sand S and gravel G. The collision surface 32a bounces the sand S and gravel G that collide as shown by arrow 7e toward the center of the width of the material loading surface 2a of the second conveyor 2 as shown by arrow 7f.

Here, a comparative example will be described with reference to Figs. 11(A) and 11(B). Figs. 11(A) and 11(B) show a schematic diagram of the material that collides with the transfer chute 130 of the comparative example being used and bounces back. The transfer chute 130 is provided with a collision plate 132 whose collision surface 132a is a flat surface. When the first conveyor 1 and the second conveyor 2 are arranged to cross each other, the conveying direction of the second conveyor 2 is the back side of the paper in Fig. 11(A) and the upper side of the paper in Fig. 11(B). In this case, the sand S and gravel G, which have different bouncing distances, fall at different positions in the width direction of the material mounting surface 2a of the second conveyor 2. In other words, the gravel G falls on the side closer to the first conveyor 1, and the sand S falls on the side farther from the first conveyor 1. Therefore, the sand S and gravel G are separated along the width direction of the material mounting surface 2a. In contrast, in the first variant, sand S and gravel G can be mixed by colliding them with the curved collision surface 32a.

Even when the upstream and downstream conveyors are arranged to cross each other, the radius of curvature R of the collision surface 32a shown in FIG. 12 is set to 0.3 to 1.1 times the overall belt width W of the first conveyor 1, and more preferably 0.5 to 0.6 times. This allows the materials to be mixed effectively. Even when the upstream and downstream conveyors cross at an angle other than perpendicular, the use of a transfer chute with a curved collision surface 32a promotes mixing of the materials. In this case, the positional relationship of the transfer chute to the downstream end of the upstream conveyor, the opposing direction, etc. can be appropriately adjusted.

(Second Modification)
Next, the second modified example will be described with reference to Fig. 13(A) and Fig. 13(B). In the second modified example, instead of the second input device 15 shown in Fig. 1, a second input device 150 is provided. The second input device 150 is provided with an enclosure 16 on the first conveyor 1 instead of the humidifier 15c. The enclosure 16 has openings 16a on both the upstream side and the downstream side. The sand S transported by the first conveyor 1 passes through the inside of the enclosure 16. Each opening 16a is provided with a curtain part 16a1 in the shape of a curtain. The curtain part 16a1 is formed by arranging a plurality of rectangular rubber plates in the width direction of the material mounting surface 1a. A water supply nozzle 17 as a first water supply device is attached to the enclosure 16, and the water supply nozzle 17 sprays mist-like water into the enclosure 16. The mist-like water fills the enclosure 16. A feeder 16b is connected to the enclosure 16. The bentonite B in the hopper 15a is discharged into the enclosure 16 via the feeder 15b. The bentonite B supplied into the hopper 15a reaches above the sand S loaded on the material loading surface 1a of the first conveyor 1 while absorbing moisture in the enclosure 16, and is transported downstream. The bentonite B can absorb the mist-like moisture and contain an appropriate amount of moisture without becoming ball-shaped.

Downstream of the enclosure 16, gravel G is supplied from the third input device 20, as in the example shown in Figure 1, and is transported further downstream, and finally accumulated in the accumulation area D as mixed soil M.

Here, to summarize the effects of the embodiments described in this specification, according to the mixing device 100 of the embodiment, moisture is supplied to the material at each material input section before it reaches the material loading surface, so the moisture content of each material can be adjusted without supplying water directly to the conveyor.

In this case, by supplying water to at least one of the hopper and feeder provided in the material input section, it is possible to avoid supplying water directly to the conveyor.

In addition, by spraying mist-like moisture, the material being fed can be evenly watered, and the material can be made to have absorbed moisture evenly. In particular, when watering bentonite B, spraying mist-like moisture can supply water to the entire bentonite B, preventing the bentonite B from forming balls. It can also prevent dust from being generated.

The mixing device 100 of this embodiment is equipped with a collision surface 32a that faces the downstream end of the upstream conveyor and causes multiple materials discharged from the downstream end to collide with each other and fall onto the downstream conveyor, and the collision surface is curved in a concave shape to promote mixing of the materials. The collision surface 32a has a radius of curvature that is 0.3 to 1.1 times the overall belt width of the upstream conveyor, thereby enabling the materials to be effectively mixed.

The mixing device of this embodiment further includes a water supply nozzle 25 that supplies water to the mixed material discharged from the conveyor, making it possible to adjust the final moisture content of the mixed soil M. At this time, the amount of water to be supplied is calculated based on the actual moisture content measured by the continuous moisture meter 27 as a moisture content measuring section and a preset target moisture content, and the water is supplied, making it possible to accurately adjust the moisture content of the mixed soil M.

Second Embodiment
Next, a mixing device 200 of the second embodiment will be described with reference to Figures 14 and 15. The mixing device 200 includes a fourth conveyor 4 between the first conveyor 1 and the second conveyor 2. A crushing and mixing section 50 is provided above the material loading surface 4a of the fourth conveyor 4. In the first embodiment, the third input device 20, which inputs gravel G to the material loading surface 1a of the first conveyor 1, has been moved so as to input gravel G to the material loading surface 4a of the fourth conveyor 4. The third input device 20 is disposed downstream of the crushing and mixing section 50. The gravel G input by the third input device 20 is not subject to crushing by the crushing and mixing section 50.

The mixer 200 is equipped with a first input device 10, similar to the mixer 100 of the first embodiment. While the first input device 10 in the mixer 100 inputs sand S, the first input device 10 in the mixer 200 inputs mudstone (sandstone). Mudstone (sandstone) is one of the materials that needs to be crushed or broken down when producing mixed soil M. The mixer 200 can also be applied when other materials that need to be crushed or broken down are input instead of mudstone (sandstone) or together with mudstone (sandstone).

A third transfer chute 30c is disposed at the transfer point between the first conveyor 1 and the fourth conveyor 4, and a fourth transfer chute 30d is disposed at the transfer point between the fourth conveyor 4 and the second conveyor 2. A fifth transfer chute 30e is provided at the transfer point between the second conveyor 2 and the third conveyor 3. These transfer chutes are the same as the first transfer chute 30a and the second transfer chute 30b in the first embodiment, so a detailed description thereof will be omitted.

In addition, other basic configurations are common to the mixing device 100 of the first embodiment, so the common components are given the same reference numbers in the drawings and detailed descriptions are omitted.

Now, the crushing and mixing section 50 will be described with reference to FIG. 15. The crushing and mixing section 50 includes a drum 51 and a rotating member 52 that is rotatably arranged within the drum 51. The rotating member 52 includes a shaft member 52a, a bearing member 52b that rotatably supports the shaft member 52a, an impact member 52c, and a rotating shaft side pulley 52d. A ball bearing can be used for the bearing member 52b, and an angular ball bearing can be used to improve the rotational accuracy and rigidity of the shaft member 52a.

The crushing and mixing section 50 also includes a lid section 53 that is attached to the drum 51. The lid section 53 is provided with an inlet 53a. The rotating member 52 is rotated by a motor (not shown) via a motor-side pulley and a drive belt (not shown).

As the rotating member 52 is driven to rotate, the impact member 52c rotates. The rotating impact member 52c collides with the third transfer chute 3c and falls, crushing the mudstone that has been put into the drum 51 together with the bentonite B from the inlet 53a. The bottom of the drum 51 is open, and the crushed mudstone falls downward.

In this embodiment, as shown in FIG. 14, the fourth conveyor 4 is disposed below the crushing and mixing section 50, so that the crushed mudstone and bentonite B are supplied onto the material loading surface 4a of the fourth conveyor 4 and transported. Then, gravel G is supplied from the third input device 20 onto the crushed mudstone.

The mudstone, bentonite B, and gravel G are mixed during the transportation process by colliding with the fourth transfer chute 30d and the fifth transfer chute 30e.

In this way, the mixing device 200 of this embodiment can transport materials that require crushing or disintegration while mixing them with other materials to obtain mixed soil M. In other words, by adopting the mixing device 200, the range of materials to be selected for the mixed soil M can be expanded.

The above-described embodiment is a preferred example of the present invention. However, the present invention is not limited to this, and various modifications are possible within the scope of the present invention. For example, in the first embodiment, sand S, bentonite B, and gravel G are fed into the first conveyor 1 in this order, but the order in which the materials are fed and the number of times they are fed can be changed as appropriate, such as feeding in the order sand S, bentonite B, sand S, and gravel G. The materials to be fed can also be selected as appropriate. Furthermore, mist-like moisture can be supplied to materials other than bentonite B, such as sand S and gravel G.

REFERENCE SIGNS LIST 1 First conveyor 1a, 2a, 3a, 4a Material loading surface 1b, 2b, 3b Downstream end 2 Second conveyor 3 Third conveyor 4 Fourth conveyor 5 Water tank 6 Control unit 10 First input device 10a, 15a, 20a Hopper 10b, 15b, 20b Feeder 11, 17, 21 Water supply nozzle (first water supply unit)
15, 150 Second input device 20 Third input device 25 Water supply nozzle (second water supply section)
27 Continuous moisture meter 30a to 30e Transfer chute 35 Discharge chute 50 Crushing and mixing section 100, 200 Material mixing device

Claims (7)

A plurality of material input units for inputting a plurality of materials including a material made of bentonite and at least two or more materials including sand and gravel, which are used for preparing the mixed soil;
an upstream conveyor that conveys the plurality of materials input by the material input unit;
A downstream conveyor disposed downstream of the upstream conveyor;
a first water supply unit that supplies moisture to the plurality of materials from the material input unit before the materials reach a material loading surface of the upstream conveyor;
a transfer chute provided at a transfer section between the upstream conveyor and the downstream conveyor, the transfer chute having a collision surface for causing the plurality of materials discharged from the upstream conveyor to collide with each other and drop onto the downstream conveyor,
The material input section into which a harder material is input among the at least two or more kinds of materials is provided downstream of the upstream conveyor,
The transfer chute causes the at least two or more types of materials transported on the upstream conveyor to collide with the collision surface, thereby varying the rebound distance depending on the hardness of the at least two or more types of materials. The upstream conveyor and the downstream conveyor cross each other at the transfer section,
2. The material mixing apparatus according to claim 1 , wherein the impact surface of the transfer chute disposed in the transfer section is concavely curved. 3. The material mixing apparatus according to claim 1 , wherein the collision surface has a radius of curvature that is 0.3 to 1.1 times the overall width of the belt of the upstream conveyor. The material mixing device according to claim 1 , further comprising a second water supply section that supplies water to the mixed material, which is a mixture of the plurality of materials and falls toward a pile of the mixed soil. a moisture content measuring unit for measuring an actual moisture content of the mixed material being conveyed;
a control unit that calculates an amount of water to be supplied to the mixed material so that the moisture content of the mixed material becomes the target moisture content based on the actual moisture content and a preset target moisture content of the mixed material, and controls the second water supply unit to supply the amount of water to the mixed material;
5. The material mixing apparatus of claim 4 including: The material mixing device according to any one of claims 1 to 5 , further comprising a crushing and mixing section into which two or more types of materials are added from among the plurality of materials, and which crushes and mixes the two or more types of materials that have been added. When a plurality of materials including a material made of bentonite and at least two or more materials including sand and gravel are put on a first conveyor , a harder material among the at least two or more materials is put on the first conveyor later ;
conveying the plurality of materials fed by the first conveyor ;
supplying moisture to the plurality of ingredients before the plurality of ingredients reach the first conveyor and are mixed on the first conveyor;
A step of causing the materials conveyed by the first conveyor to collide with a collision surface and drop the materials onto a second conveyor while varying the rebound distances according to the hardness of the at least two or more types of materials;
A material mixing method comprising:

Images