JP2009101521A - Method and apparatus for supplying concrete reinforcing short fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for dispersing/supplying reinforcing short fibers quantitatively and uniformly when concrete is kneaded. <P>SOLUTION: In the method for supplying the concrete reinforcing short fibers, a prescribed amount of the short fibers are supplied into a rotor in the shape of a cylindrical or polygonal tubular basket which includes a meshed lattice on the periphery, the rotor is rotated, and the short fibers are sent out from the meshed lattice, transferred pneumatically, dispersed, and supplied into the concrete being kneaded. The apparatus for supplying the concrete reinforcing short fibers includes the basketlike rotor, the rotary driving part of the rotor, a receiving part for receiving the short fibers sent out from the barrel part periphery of the rotor, a transfer part for transferring the short fibers collected in the receiving part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, reinforcing short fibers (hereinafter sometimes simply referred to as “short fibers”) are quantitatively and evenly distributed and supplied when kneading concrete, mortar, etc. (hereinafter collectively referred to as “concrete”). The present invention relates to a method and an apparatus thereof.

Conventionally, organic fibers such as steel fibers, vinylon, and polypropylene are known as fibers for cement-based molded articles such as mortar and concrete.
Recently, polypropylene fibers have been attracting attention by taking advantage of the cost advantage that the mass ratio is the smallest in the cement molding because it does not rust, has excellent cement alkali resistance, and has the lowest specific gravity among the synthetic fibers. It has been used for tunnel lining concrete.
However, in order to increase the strength of the concrete with these short fibers, reinforcing short fibers made of polypropylene or the like and having a single yarn fineness of 200 to 10000 dtex and a length of about 5 to 100 mm are evenly dispersed in the concrete. This is very important. For this purpose, it is desirable to supply it uniformly and continuously at a predetermined kneading time.
On the other hand, concrete reinforcing short fibers are manufactured by a fiber maker, etc., packed in a predetermined mass unit, and supplied. However, at the stage of unpacking and using, the short fibers are in the form of a compacted mass. First, there was a problem of how to defibrate short fibers.
Also, when the defibrated short fibers are fed into the concrete, depending on the amount and manner of supply, it takes a long time to get entangled with the stirring blades installed at the supply port inside the mixer or evenly mixed. Then, the short fibers are entangled with each other to easily form a lump fiber ball, and it becomes difficult to mix the short fibers evenly in the concrete.

With respect to the problem of defibration of the packed short fibers, a resin fiber supply device that disperses the short fibers by two front and rear rotating bodies has been proposed as a short fiber loosening treatment section (see Patent Document 1).
Further, as a method of loosening the massive fiber group, the massive fiber group is supplied onto a pair of cylindrical pin groups having a large number of pins on the outer periphery of the rotating shaft, and the fiber group is made to flow on the cylindrical pin group. A method of unwinding and taking out from the lower side of the hopper has been proposed (see Patent Document 2).
However, the fiber disentanglement methods of Patent Document 1 and Patent Document 2 are both methods of rotating a pin array attached to the rotating shaft, and the short fibers are intermittently dropped or the short fibers are entangled. There were problems such as becoming tangled around the pins and the rotating shaft.

In addition, as a continuous quantitative supply method to the concrete mixer, a supply hopper, a transfer unit that transfers the fiber material while vibrating and appropriately dispersing, and a supply that supplies the concrete material to which the transferred fiber material is kneaded. The feed hopper is provided with a grid-like sieve part, and the supply part is provided with an air ejection device that ejects air in a direction intersecting the transfer and supply direction with respect to the fibrous material. A fiber material supply device has been proposed (Patent Document 3).
However, the fiber material supply device described in Patent Document 3 is used by directly contacting the bowl-shaped transfer portion of the device with the hopper portion of the concrete mixer, and supplies it to the concrete mixer truck, agitator truck, etc. on site. It is difficult to use as a device in the case of.

In addition, as a continuous quantitative supply of short fibers in a bundle of fine fibers mixed and added to the short fiber-mixed concrete, the short fibers fed out and measured from the opening only by friction with the transparent rotating drum are dispersed to the concrete. There has been proposed a continuous fiber constant supply device to be added to (see Patent Document 4).
However, the fiber continuous quantitative supply device described in Patent Document 4 has a fiber feed amount of about 330 to 640 g in 120 seconds. For example, in order to finish the mixing of concrete in about 3 minutes per batch, The supply amount is insufficient.
As described above, a method for supplying reinforcing short fibers and a compact supply device that can be continuously distributed and supplied to a concrete mixer truck or a hopper portion of an agitator have not been developed.

JP 2006-37241 A Japanese Patent Laid-Open No. 10-131069 Japanese Patent Laid-Open No. 7-299816 JP 9-38942 A

  Accordingly, the present inventors have aimed to provide a method and apparatus for quantitatively and evenly supplying reinforcing short fibers while mixing concrete.

The present inventors supply a predetermined amount of concrete reinforcing short fibers inside a cylindrical or polygonal cylindrical cage having a mesh grid on the outer periphery, and rotating the cage to rotate the mesh grid. It has been found that the short fibers are fed out, and are transported in air and supplied to the concrete being kneaded in a dispersed state, whereby the short and constant fibers can be distributed in a quantitative and uniform manner and the above-mentioned problems of the prior art can be solved.
That is, the present invention
(1) A predetermined amount of concrete reinforcing short fibers are supplied to the inside of a cylindrical or polygonal cylindrical bowl-shaped rotating body having a mesh-like grid on the outer periphery, and the bowl-shaped rotating body is rotated to rotate the short mesh from the mesh-like grid. A method for supplying short fibers for reinforcing concrete, characterized in that the fibers are fed out and air-transferred to supply the fibers to the concrete being kneaded in a dispersed state,
(2) The method for supplying short fibers for concrete reinforcement according to the above (1), wherein the feeding mass per unit time of the short fibers is controlled by the number of rotations of the rotating body,
(3) The residual short fiber mass (Wr) is detected every predetermined time, the mass difference ratio is calculated based on the theoretical residual amount (Wt) at the predetermined time, and the saddle-shaped rotating body is calculated based on the calculation result. The method for supplying short fibers for concrete reinforcement according to (1) or (2), wherein the number of rotations is controlled
(4) a cylindrical or polygonal cylindrical bowl-shaped rotating body having a volume capable of accommodating a predetermined amount of concrete reinforcing short fibers and having a mesh-like lattice on the outer periphery; and a rotation driving unit of the bowl-shaped rotating body; A supply device for short fibers for concrete reinforcement, comprising: a receiving portion for the short fibers drawn out from the mesh lattice of the bowl-shaped rotating body; and a transfer portion for transferring the short fibers assembled in the receiving portion;
(5) Based on the measurement unit of the short fiber mass of the bowl-shaped rotator, the calculation unit that detects the measured residual short fiber mass Wr and performs the comparison operation based on the theoretical residual amount Wt in the predetermined time, and the calculation result A supply device of short fibers for concrete reinforcement according to (4), further comprising a control unit for controlling the rotational speed of the bowl-shaped rotating body;
(6) The short fiber mass measuring device for supplying concrete reinforcing short fibers according to (5), wherein the measurement unit of the short fiber mass is a load cell,
(7) Any of the above (4) to (6), wherein the mesh has a square lattice shape, and one side of the square lattice is 1.1 × Lmm to 1.5 × Lmm with respect to the short fiber length Lmm. The concrete reinforcing fiber supply device according to any one of (4) to (7) above, and (8) the concrete reinforcing short fiber supply device according to any one of (4) to (7),
Is to provide.

The method for supplying the short fiber for reinforcing concrete according to the present invention can supply the short fiber continuously to the hopper portion of the concrete mixer at a predetermined time at a predetermined supply speed. Can be saved.
The concrete reinforcing fiber supply device of the present invention is a device that can embody the above-described method of supplying the concrete reinforcing short fiber of the present invention. Concrete in which short fibers are uniformly dispersed can be produced.

  The present invention will be described below with reference to the accompanying drawings. 1 to 8 show an embodiment of the method for supplying concrete reinforcing short fibers and the apparatus for supplying concrete reinforcing short fibers according to the present invention.

The short fibers used in the method for supplying concrete reinforcing short fibers and the concrete reinforcing fiber supply apparatus of the present invention are synthetic fibers having a single yarn fineness of 200 to 10000 dtex and a fiber length of about 5 mm to 100 mm. Particularly preferable short fibers include the following.
The present applicants have sufficient fixing power with cement paste as a reinforcing short fiber for cement-based molded bodies for civil engineering and construction work, and have good fiber-opening properties when mixed in the feed, Patent application No. 2006-261192 was filed for reinforcing short fibers for cement-based molded articles that can achieve good dispersibility in Japan. This short fiber has no surface irregularities at the part where the short fibers come into contact with each other when the short fibers are opened, and the surface area of the short fibers is increased in order to secure the fixing property with the cement paste. Specifically, a shape that can remarkably enhance physical coupling is formed. Specifically, a concave portion formed by an embossing roller at a specific depth and a specific interval is formed on a substantially polygonal side portion or groove bottom portion having a protrusion. It has been formed.
In the embodiment shown in the figure, the applicant previously mentioned the X-section shown in the embodiment of the above-mentioned application, and a rhombus-shaped concave shape was formed on the upper and lower groove bottoms of the X-section, the fineness of 3300 dtex, the tensile strength 509 N / mm ² , a short fiber for reinforcing concrete with a fiber length of 40 mm (manufactured by Ube Nitto Kasei Co., Ltd., trade name “Simrock”) was used. Further, 4.5 m ³ of concrete was used as a kneading unit (1 batch), and the short fiber required for the mixing was 12.3 kg. The short fiber is packed in a polyethylene bag, for example, in units of 12.3 kg, and stored in a plastic cardboard case (return box) having an inner size of 55 cm × 55 cm × 62 cm, and the apparent bulk specific gravity is approximately 65 kg. / M ³ .

FIG. 1 is an explanatory diagram of the overall configuration of an example of a concrete reinforcing fiber supply device of the present invention. The supply device 1 shown in the figure includes at least a bowl-shaped rotator 2 (hereinafter, also referred to as “drum”), a receiving unit 3, a transfer unit 4, and further includes a control unit 5, The component member is fixed on a gantry 7 to which four wheels 6 for movement are attached, and has a jack 8 with a handle for fixing the gantry 7.
In addition, a receiving plate 9 can be provided in a part of the bowl-shaped rotating body in order to prevent the short fibers from dropping into the receiving portion 3 as they are introduced. Furthermore, the receiving plate 9 can be always returned to the lower fixed position when the short fiber is put in by setting the stop position by, for example, a limit switch or a proximity sensor by returning to the origin.
The receiving plate 9 is preferably taken to be about 1/6 to 1/4 of the net area of the bowl-shaped rotating body 2, for example. In addition, the receiving plate 9 can be structured to be movable in a satellite manner on the outside of the cage instead of being attached to the cage-shaped rotating body. The structure is below when the short fibers are put into the bowl-shaped rotator 2 and is retracted upward when the short fibers are sprinkled and dropped.
FIG. 2 is a rear view of the concrete reinforcing short fiber supply device shown in FIG. 1, and the short fibers are transferred through the pipe 402 by the wind pressure of the blower B1. The highest part of the pipe 402 is attached at a height of about 4 m.
The overall size is about 2.3 m in width, 1.4 m in depth, 4 to 3 m in height, and the total weight is about 400 kg.

FIG. 3 is an explanatory diagram of the main part of the front face in the embodiment shown in FIG. 1, and FIG. 4 is an explanatory diagram of the main part of the left side surface in the same embodiment. Moreover, FIG. 5 is a figure which shows the condition which has supplied the short fiber to the concrete mixer truck by the supply apparatus of the short fiber for concrete reinforcement of this invention.
As shown in FIG. 3, the bowl-shaped rotator 2 has a diameter of 800 mm and a length of 800 mm, and ¾ of the outer peripheral surface 201 has a mesh lattice 202 and ¼ of the supply opening 203. A steel plate flange 205 having a thickness of approximately 2 to 3 mm, a thickness of 25 mm, a diameter of 230 mm, and a center shaft mounting boss 206 having four screw holes are provided at both ends. The center shaft 207 has a diameter of 30 mm, supports the bowl-shaped rotator 2 in the center, and is inserted into two bearings 209 fixed on the base block 208 on the gantry 7 at both ends. One shaft end of the center shaft 207 is connected to a motor 501 with a brake via a coupling 210 and is driven to rotate.
In addition, although the bowl-shaped rotating body 2 is cylindrical in this embodiment, it may be a polygonal cylinder such as a hexagon or an octagon.

For example, a 3 mm diameter SUS304 stainless steel rod (wire) welded wire mesh or the like can be used as the mesh lattice 202. The mesh is preferably a square lattice, and the size of one side of the square lattice is short fiber. From the viewpoint of ease of feeding control, the fiber length L is 1.05 L to 2.0 L, more preferably 1.1 L to 1.7 L, and particularly preferably 1.2 L to 1.5 L. it can. More specifically, a 50 mm square mesh is used for a short fiber length of 40 mm.
In addition, it is more preferable that the inside of the bowl-shaped rotator 2 has a structure in which the rotation shaft does not penetrate. If the rotating shaft is penetrating, the shaft may be disturbed and the amount of short fibers fed may be distorted. Therefore, the amount of feeding can be controlled more precisely by using the above structure. In addition, there is an advantage that it is easy to insert short fibers into the bowl-shaped rotating body 2.

  The receiving portion 3 includes an inverted truncated pyramid (square funnel) -shaped shooter portion 301 positioned below the bowl-shaped rotator 2 and a cover 302 that extends above the shooter section and surrounds the outer periphery and the upper portion of the bowl-shaped rotator 2. have. The cover 302 also has a door 303 that can be opened when short fibers are supplied. At least one surface of the cover 302 is preferably composed of a transparent plastic plate so that the state of feeding (falling) of short fibers from the bowl-shaped rotating body can be observed.

The lower part of the shooter 301 is connected to the transfer unit 4. The short fibers collected and dropped in the transfer unit 4 are transferred from the pipe 401 through the pipe 402 by the suction force and / or wind pressure by the blower B1, and supplied to the concrete mixer (including agitator) hopper H as shown in FIG. The In consideration of the hopper H of the concrete mixer truck, the upper part of the pipe 402 is about 4 m or more. On the other hand, the height of the pipe 402 is inconvenient when transporting and moving the apparatus. It has become.
In addition, when the transfer in the pipe 401 from the lower part of the shooter 301 to the blower B1 is not smooth, a separate auxiliary blower B2 may be installed and transferred to the pipe 402 side by wind pressure.

The control unit 5 adjusts the feeding amount of the short fiber by controlling the rotational speed of the hook-shaped rotator 2 by controlling the drive motor 501 of the hook-shaped rotator 2 with an inverter. The control unit 5 includes a pilot lamp, a rotation number display unit, a time display unit, a weight display unit, a calculated weight display unit, and the like, and necessary settings can be set with a touch panel. As the drive motor 501, an AC200V, 1/240 brake motor (0.2 kW) was used.
The data of the control unit is obtained from the mass of short fibers detected by the load cell 502 as a measurement unit installed at the lower part of the base block 208. In consideration of the balance with the bearing 209 and the like, four load cells 502 are arranged in the front-rear direction of the lower part of the left and right base blocks 208 of the bowl-shaped rotating body 2 in FIG. The load cell 502 measures the total mass of the saddle-like rotating body including the bearing, the base block, the tare by the motor 501, and the short fibers, and subtracts the tare from them to calculate the short fiber mass.
Since there are four load cells 502, the sum of the four detection values is converted into data as mass. In this example, four load cells manufactured by Toyo Sokki Co., Ltd., part number: MODEL 1330, which can handle a load of 50 kg, were used as load cells.

FIG. 6 is an explanatory diagram showing a control method of the method for supplying short fibers for concrete reinforcement according to the present invention. The short fibers supplied to the bowl-shaped rotator 2 with the mass of the packing unit begin to be fed out from the mesh lattice with the rotation of the bowl-shaped rotator, and supplied to the concrete mixer hopper H through the collection and transfer unit. Once started, the mass detected by the load cell 502 will decrease sequentially.
The mass difference ratio is calculated based on the detected mass (Wr) and the theoretical residual mass (Wt) when supplied within a predetermined supply time, and the rotational speed of the bowl-shaped rotating body is calculated from the supply speed to be supplied within the remaining time. The rotation speed of the motor 501 is calculated and controlled by the inverter control panel.
The motor 501 employs a 1/240 brake motor. When supplying 12 kg of reinforcing short fibers in 3 minutes (180 seconds), the frequency of the motor 501 is approximately 40 to 80 Hz (Hertz), and the control cycle is preferably about one rotation or within about 10 seconds.

FIG. 7 shows an example of the control procedure. In the control procedure shown in the figure, the preparation-start stage control system (a), timer display control system (b), automatic control system (c), constant speed control system (d), end-stop control system (e) Broadly divided.
First, the preparation-start stage control system (a) activates the push button switch (PB) of the control panel 5 in S (hereinafter referred to as “step”) 1 as shown in FIG. 7- (1). In step 2, the motor 502 rotates the bowl-shaped rotator 2 at a frequency of 20 Hz. In step 3, the origin sensor attached to the predetermined position of the bowl-shaped rotator and the predetermined position of the gantry is activated. The body 2 stops at the origin position. The origin position is set so that the supply opening of the short fiber (hereinafter sometimes referred to as “raw material”) returns to a fixed position. In step 6, a raw material having a predetermined mass is supplied, and in step 7, raw material weight measurement by a load cell and an initial set speed are input to the touch panel of the control panel 5 and supplied by an automatic control system (c), or a constant speed control system. The changeover switch of whether to supply in (d) is switched to either.
When the start PB switch is activated in step 8, the blower of the transfer unit 4 is activated in step 9, and after 2 seconds have elapsed in step 10, the timer display control system (b) and the automatic control system (c) or constant speed control. Transferred to the series of system (d).

  As shown in FIG. 7- (2), in the timer display system (b), in steps 11 to 15, the timer-activated green patrol light display lamp is turned on, and the yellow patrol light is turned on and the buzzer sounds and operates in 60 seconds from the start of operation. After 120 seconds from the start, the red patrol light is turned on and the buzzer sounds, and the system shifts to the end-stop series (e).

When the automatic control system (c) is switched at step 21, the automatic control switching is confirmed at step 21, the initial drum speed is rotated at 6.25R / min (motor: 50Hz) at step 22, and at step 23, When 6 rotations are measured by the tachometer, the metering control is started in step 24.
First, in steps 25 and 26, the (mass) theoretical value (* 1) per rotation is calculated. The (mass) theoretical value (* 1) is derived from the following calculation formulas (1) to (3).
-Initial total mass (g) / feeding time (0.1 seconds) = unit time feeding amount (g) (1)
-Unit time feed amount (g) x elapsed time (0.1 seconds) = mass change theoretical value (g) (2)
-Initial total mass-mass change theoretical value (g) = mass theoretical value (Wt) (3)
Next, in step 27, it is compared with the current value (Wr) after a lapse of a predetermined number of seconds from the start, and in step 28, it is determined whether the mass difference is within an allowable range of 100 g. Is continuously fed out at the same rotational speed until the final time (170 seconds). On the other hand, if it is outside the allowable range, mass difference calculation (* 2) is performed in step 29. The mass difference is calculated from the following calculation formula (4) and expressed in%.
・ [Current mass value (Wr) ÷ Theoretical mass value (Wt)] × 100 = Mass difference ratio (4)
Next, rotation speed (frequency) correction (* 3) is performed in step 30 according to the mass difference ratio. The rotational speed (frequency) correction is performed by calculation using the calculation formula (5).
・ [Previous (previous) frequency (Hz) x Mass difference ratio (%)] / 100 = Correction (current) frequency (Hz) (5)
(However, the initial frequency is 50 Hz.)

After each of the above steps, it is determined whether or not the mass difference is within the allowable range of 100 g in the above-described step 28, and continues at the same rotation speed until the final time (170 seconds) in step 31 as in the case of Yes. When the final time (170 seconds) is reached, in step 32, the final frequency is changed to 120 Hz (rotating body: 15 R / min), and in step 33, the feeding is continuously repeated until 180 seconds have passed.
When 180 seconds elapse in step 33, the process proceeds to the end-stop control system (e) shown in FIG. 7- (3), the buzzer 2 rings in step 16, and the presence or absence of the remaining amount of raw material is determined in step 17. If there is no residue, the stop push button in step 19 is activated, and in step 20, the bowl-shaped rotating body (drum) is stopped, the blower is also stopped, and one batch supply operation is completed.

On the other hand, when it is determined from the results of automatic control operation or the like that the short fibers can be fed almost uniformly at a constant speed, the short fibers are fed by the constant speed control system (d) shown in FIG. You may supply.
In the constant speed control system (d), for example, in step 34, the inverter motor is rotated at 50 Hz (drum: 6.25 R / min), and in step 35, it is rotated up to 180 seconds. What is necessary is just to make it transfer to a stop control system (e).

FIG. 8 shows the relationship between the elapsed time and the feed amount when the inverter motor is controlled at a constant speed of 40, 60, and 80 Hz. In the figure, at 60 Hz, the theoretical feed amount is converged.
FIG. 9 shows the result of initially rotating the drum at 50 Hz and then operating automatically.

  As described above, according to the method and apparatus of the present invention, when supplying the same amount of short fibers to the concrete in the same amount, it was necessary to work by two people, but it can be performed by one person, and This work is also a monitoring work other than the raw material supply, and can save labor and reduce the work. Further, since the short fibers can be supplied almost uniformly by a certain amount, the short fibers are uniformly dispersed in the concrete in a relatively short time, so that the concrete kneading time can be shortened and the concrete quality can be made uniform.

  The method and apparatus for supplying short fibers for reinforcing concrete according to the present invention can be used for the production of concrete containing short fibers.

It is a whole composition side view of a short fiber supply device for concrete reinforcement in one embodiment of the present invention. It is a rear view in embodiment of FIG. It is a front principal part explanatory drawing in embodiment of FIG. FIG. 2 is a left side side explanatory view of the embodiment of FIG. It is supply condition explanatory drawing of the short fiber for reinforcement to the mixer truck hopper by the short fiber supply apparatus for concrete reinforcement of this invention. It is explanatory drawing of the control method in the short fiber supply method for concrete reinforcement of this invention. It is a flowchart of the process sequence performed in the calculation control part of the short fiber supply apparatus for concrete reinforcement shown in FIG. It is a comparison figure of time passage and remaining weight (feeding amount) in the change of the frequency of a motor. It is a figure which shows the result of having rotated the drum at 50 Hz initially, and driving | running by the automatic control system (c) after that.

Explanation of symbols

1 Short fiber feeder for concrete reinforcement 2 Drum-like rotating body (drum)
DESCRIPTION OF SYMBOLS 3 Receiving part 4 Transfer part 5 Control part 6 Wheel for movement 7 Base 8 Jack with handle 9 Receiving board 201 Outer periphery (outer peripheral surface)
202 Mesh grid 203 Supply opening 204 Lid 205 Flange 206 Center shaft mounting boss 207 Center shaft 208 Base block 209 Bearing 210 Coupling 301 Shooter 302 Cover 303 Opening door 401 Pipe 402 Pipe 403 Pipe holder 501 Driving motor 502 Measuring unit (load cell)
503 Handwheel turning handle B1 Blower S Step

Claims (8)

  A predetermined amount of concrete reinforcing short fibers are supplied to the inside of a cylindrical or polygonal cylindrical bowl-shaped rotating body having a mesh grid on the outer periphery, and the short fibers are fed out from the mesh grid by rotating the bowl-shaped rotating body. A method for supplying concrete reinforcing short fibers, characterized in that it is air-transferred and supplied in a dispersed manner to the concrete being kneaded.   2. The method of supplying concrete reinforcing short fibers according to claim 1, wherein the feeding mass per unit time of the short fibers is controlled by the number of rotations of the rotating body.   The remaining short fiber mass (Wr) is detected at every elapse of a predetermined time, the mass difference ratio is calculated based on the theoretical remaining amount (Wt) at the predetermined time, and the number of rotations of the hook-shaped rotating body is calculated based on the calculation result. The method for supplying short fibers for concrete reinforcement according to claim 1 or 2, wherein the control is performed.   A cylindrical or polygonal cylindrical rod-shaped rotating body having a volume capable of accommodating a predetermined amount of concrete reinforcing short fibers and having a mesh-like lattice on the outer periphery, a rotation driving portion of the rod-shaped rotating body, and the bowl-shaped An apparatus for supplying short fibers for concrete reinforcement, comprising: a receiving portion for receiving the short fibers fed from a mesh lattice of a rotating body; and a transfer portion for transferring the short fibers assembled in the receiving portion.   A measuring unit for measuring the short fiber mass of the bowl-shaped rotating body, a calculating unit for detecting the measured residual short fiber mass (Wr) and calculating a mass difference ratio based on the theoretical residual amount (Wt) in the predetermined time; The apparatus for supplying short fibers for concrete reinforcement according to claim 4, further comprising a control unit that controls the number of rotations of the bowl-shaped rotator based on the calculation result.   The apparatus for supplying short fibers for concrete reinforcement according to claim 5, wherein the measurement unit of the short fiber mass is a load cell.   The mesh is a square lattice shape, and one side of the square lattice is 1.1 × Lmm to 1.5 × Lmm with respect to the short fiber length Lmm. Short fiber feeder.   The apparatus for supplying concrete reinforcing short fibers according to any one of claims 4 to 7, comprising a moving wheel.

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