JP2742889B2 - Method for producing steel fiber for concrete reinforcement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a steel fiber for concrete reinforcement used for reinforcing concrete by mixing it with concrete.

[0002]

2. Description of the Related Art Conventionally, concrete has been widely used in the field of civil engineering and construction. Although this concrete has a high compressive strength, its tensile strength is as low as about 1/10 of the compressive strength, so that a reinforcing bar or a steel wire is usually used as its reinforcing material. Furthermore, in recent years, the diameter is 0.4 to 1.0 m.
Steel fiber reinforced concrete (SFRC) in which steel fibers having a length of 25 to 80 mm and a volume ratio of concrete to concrete of about 0.3 to 2% are mixed with concrete has been used. Such concrete reinforcing steel fibers are:
In order to improve the adhesion to concrete, both ends are bent or corrugated to be used.
However, conventional steel fibers are usually bent in a direction perpendicular to a flat plate or an uneven plane (transverse bending portion), so that the shape improves the adhesion, but the dispersibility is poor and the steel fibers are entangled with each other, so-called The fiber ball phenomenon easily occurs and the second moment of area is small,
There is a problem that the deformation resistance is small.

[0003] In order to solve these problems, the inventor of the present invention has devised a device having a vertically long and flat cross section and having a bent portion (longitudinal bent portion) at both ends or the entire length in the same plane as the deflected plane. . This structure is flat because the left and right sides are flat, so it has good dispersibility, fiber balls are less likely to be formed due to entanglement during kneading with concrete, and the width / thickness ratio is large, the second moment of area is large, and the bent part Is characterized by having a very large deformation resistance and a high reinforcing effect. However, there is a problem in manufacturing. That is, in the case of a type of steel fiber in which the bent portion projects perpendicularly to the uneven plane, that is, in the thickness direction, since the contact area with the roll is large, the roll of the paired roll in which the concave portion and the convex portion are formed respectively is provided. It can be easily manufactured by passing a steel fiber material through the gap. However, since the reinforcing steel fiber has a width / thickness of 2 or more and a bent portion is a vertical bend on the same plane as an uneven plane, The contact area is very small, so it is difficult to perform vertical bending under this condition, and the occurrence rate of variations and defective products increases. For this reason, there is no other way than to manufacture with low efficiency with expensive equipment such as press molding, and there is a problem that the manufacturing cost is high although the reinforcing property and workability are good.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems.
An object of the present invention is to provide a method capable of inexpensively and efficiently producing a steel fiber for concrete reinforcement, which has a good dispersibility and a very large deformation resistance, and provides an excellent reinforcing effect.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a steel fiber for concrete reinforcement having a vertically long and flat cross section and having bent portions at least at both ends in the same plane as the flat surface. In manufacturing, the steel wire is flattened by rolling means, and then the flat steel wire has a plurality of bending projections and a cutting blade between the bending projections, and a flat steel wire holding groove is formed in them. A grooved roll in which a plurality of formed cutting pieces are provided on the circumference and grooves for holding a flat steel wire are formed on the circumference other than the formed cutting pieces, a plurality of bending concave portions corresponding to the bending convex portions, and A plurality of formed cutting pieces having a cutting blade portion corresponding to the cutting blade portion and having a protruding portion provided before and after the bending concave portion and having a flat steel wire holding groove provided in each of these and the cutting blade portion on the circumference. A pair of forming and cutting rolls consisting of a flat roll provided The flat steel wire is supplied and restrained by the flat steel wire holding groove, and a bending portion is formed in the same plane as the flat surface by the bending convex portion and the bending concave portion while being cut by the cutting blade portion. Things. The flat steel wire is 1
Although it may be supplied to the forming and cutting rolls one by one, preferably a plurality of pieces are simultaneously supplied to the forming and cutting rolls,
Be cut off. More preferably, the flat steel wire is supplied to the flat steel wire holding groove of the forming and cutting roll in a state where a plurality of flat steel wires are stacked so that the flat surfaces are in contact with each other, and is formed and cut. The number of grooves for holding the flat steel wire of the forming and cutting roll may be one, but preferably a plurality of grooves. In addition, after flat steel wire is rolled flat,
Once wound on a bobbin, it may be supplied to a forming and cutting roll from this bobbin, but preferably rolling and forming and cutting are performed continuously without interposition of bobbin winding, and in particular, a plurality of steel wires are simultaneously rolled. It is preferable that the flat-rolled flattened steel wire is supplied to a forming and cutting roll without being wound on a bobbin, and is formed and cut. It is preferable that the forming cut pieces of the grooved roll and the flat roll are made of cemented carbide. Preferred specifications of the reinforcing steel fiber produced in the present invention are such that the width / thickness is 2 to 8 and the length / width is 20 to 45.
belongs to.

[0006]

[Function] When a round steel wire is pressure-biased to a width / thickness of 2 or more, and the pressure-biased steel wire is supplied to a forming and cutting roll that rotates in opposite directions,
Since the grooved roll as one side roll of the forming and cutting roll has a holding groove on the circumference, even a pressure-biased steel wire having poor self-sustainability is prevented from falling down and is moved in a stable posture. Each forming cut piece of the grooved roll has a plurality of bending projections, and the forming cut piece of the flat roll as the other roll of the forming cutting roll has a plurality of bending recesses. The flat steel wire has a bent portion formed on the same plane as the flat surface. In addition, since there is a pair of cutting blades between the plurality of bending protrusions and between the plurality of bending recesses, the flat steel wire is thereby cut and has a bending portion on the same plane as the uneven surface. A predetermined length of steel fiber is produced continuously. The flat roll forming and cutting piece has a retaining groove at the protruding portion and the cutting blade portion before and after the bending concave portion, and the flat steel wire is nipped and moved by the retaining groove from left, right, front and rear during cutting and the bending. Is restrained, so that bending and cutting can be performed reliably, and a reliable feed can be given to the flat steel wire, so that the production speed can be increased. If a plurality of flat steel wires are supplied to the forming and cutting roll at the same time, or if a plurality of flat steel wires are overlapped and supplied to the forming and cutting roll, productivity can be further improved. Furthermore, when multiple steel wires are simultaneously rolled and supplied directly to the forming and cutting rolls, the reinforcing steel fibers can be made continuously and continuously from the raw steel wires, and the forming and cutting speed is extremely high. Therefore, productivity can be further improved. Width / thickness 2-8,
Since it is a reinforcing steel fiber having a length / width of 20 to 45, dispersion and deformation resistance can be realized in a well-balanced manner. It can be set depending on the diameter and the position of the cutting blade.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 7 show a first embodiment of a method for producing a steel fiber for concrete reinforcement according to the present invention. FIG. 8 shows an example of a steel fiber for concrete reinforcement according to the present invention. 1 and 2, reference numerals 1a, 1a, and 1a denote a plurality of steel wires as steel fiber raw materials, and generally have a circular cross section (round steel wire). Such steel wires 1a, 1a, 1
a is wound on a bobbin and attached to suppliers (swifters) 10, 10, and 10, respectively. Reference numeral 12 denotes a rolling mill for simultaneously rolling the plurality of steel wires 1a, 1a, 1a, and is constituted by a pair of rollers 12a, 12b arranged to face each other. The rolling mill 12 and the switcher 1
Between 0, 10, and 10, a tension adjusting device 11 for keeping the length of each steel wire rod 1a, 1a, 1a constant is disposed. Each tension adjusting device 11 includes a plurality of steel wires 1a, 1
If a difference in length after rolling occurs when a and 1a are simultaneously rolled, the rotation speed of the rolling mill is synchronized with the shortest steel wire, and the excess length is accumulated. You. FIG. 3 schematically shows the tension adjusting device 11, in which a back tension unit 11a having a powder brake 110 is provided immediately adjacent to the switcher 10, and a steel wire 1a is crossed over the back tension unit 11a. The lower limit sensor 111 and the powder brake 110 for driving the powder brake 110 are provided at the upper and lower positions of the tilting arm 11c supporting the dancer roll 11b by passing the rolled flat steel wire by providing the roll 11b. Upper limit sensor 112 for turning off the drive of
Has been arranged. As a result, the surplus lengths of the steel wires 1a, 1a, 1a are detected by the lower limit sensor 111 and the upper limit sensor 112, and the corresponding powder brakes 110 of the back tension unit 11a on the supply side are individually turned on.
Since the steel wires 1a are controlled to be off, variations in the lengths of the steel wires 1a, 1a, 1a are suppressed, and the steel wires 1a can be smoothly rolled simultaneously and supplied to the next step. Reference numeral 13 denotes straightening rolls arranged on the downstream side of the rolling rolls 11 in the same number as the steel wires 1a, 1a, 1a, and each straightening roll 13 includes a plurality of rolls 13a,
13a are arranged in a zigzag pattern, and straighten flat steel wires 1b by correcting warpage and bending generated in the rolling process in the rolling mill 12.
It is a means for molding into. This straightening roll 13,1
3 and 13 are mounted on a gantry 18, and a voice 14 and a laminating roll 15 are arranged on the gantry downstream of the straightening rolls 13, 13 and 13. The voice 14 has a hole for guiding the flat steel wire 1b straightened by the straightening rolls 13, 13, 13 toward the laminating roll 15 so that the flat surfaces are aligned. In addition, straightening roll 1
A capstan roll for drawing out a steel wire may be provided between 3, 13, 13 and the voice 14 or downstream thereof. The laminating roll 15 includes a large-diameter roll 15a disposed in the front end region of the gantry 18 and a plurality of flat steel wires 1b, 1
and a pressing roll 15b for pressing the flat steel wires 1 and 2b.
b, 1b, 1b are stacked so that the respective deflected planes 100 are in close contact with each other, and are lowered in parallel with the front end face of the gantry 18.

Reference numeral 16 denotes a forming / cutting roll mounted on the front end surface of a gantry 18, which is constituted by a pair of flat rolls 17 and grooved rolls 19 which are disposed to face each other. The relationship is orthogonal to the rotation axis of the roll 15. At least one of the flat roll 17 and the grooved roll 19 is driven by a drive mechanism 20 mounted on the gantry 18. A magnetic alignment device 21 is provided below the forming and cutting roll 16. The magnetic alignment device 21 includes a magnet 21a and a magnet 21b,
1b.

FIGS. 5 to 7 show the forming and cutting roll 16.
The details are shown. First, in this example, in the flat roll 17 and the grooved roll 19, four sets of notch grooves 17B and 19B are formed at regular intervals on the circumference as shown in FIG. 5, and the notch grooves 17B and 19B are formed in these notches. Molding cutting pieces 17A and 19A are fitted therein, and are exchangeably fixed by set bolts or the like (not shown). The forming and cutting pieces 17A and 19A are preferably made of a cemented carbide in order to reduce abrasion even when the forming and cutting speed is increased. It is preferable that the cemented carbide has a hardness of, for example, 89.5 HRa or more. Flat roll 17 and grooved roll 1
9 have the same diameter, the forming cut piece 17A of the flat roll 17 and the forming cut piece 19A of the grooved roll 19 are formed.
Are configured to always mesh with the rotation of these rolls (indicated by the arrow A in the figure). In the case of the present embodiment, the length of the steel fiber 5 for concrete reinforcement to be manufactured is substantially the same as the length of the circumference because four sets of the forming and cutting pieces 17A and 19A are provided on the circumference. 1/4. The steel fiber produced in the present invention preferably has a length / width, that is, a width aspect ratio of 20 to 45. this is,
If the length / width is less than 20, the fiber length is too short and the reinforcing effect is reduced, and if the length / width exceeds 45, entanglement tends to occur. The width can be arbitrarily set according to the rolling reduction of the steel wire in the rolling process, and the length / width is realized by arbitrarily setting the diameter of the roll or the number of the forming cut pieces 17A and the forming cut pieces 19A. It is possible.

The configuration of the forming and cutting piece 17A of the flat roll 17 and the forming and cutting piece 19A provided on the grooved roll 19 will be described in detail. First, the outer peripheral surface 170 of the flat roll 17 is flat, A groove 195 for holding the flat steel wire 1b is provided in the roll surface 190 of the 19 in the circumferential direction. The width of the holding groove 195 is the flat steel wire 1
b (in the case of one wire) or laminated flat steel wire 1b
Is set appropriately by the product of the number of
b is slightly larger than the product of the number of b.
When the thickness t of the flat steel wire 1b is 0.28 mm, the groove width is set to about 1.6 mm, and when the flat steel wire 1b has a thickness t of 0.38 mm, five grooves are stacked. May have a groove width of about 2.1 mm. The holding groove 19
The depth of 5 is set slightly smaller than the width W of the flat steel wire 1b. For example, when the width W of the flat steel wire 1b is 1.15 mm, it is about 1.05 mm, and when it is 1.50 mm, it is 1.4.
Approximately 0 mm, and the width W of the flat steel wire 1b is also 0.1
It is preferable to make it shallow by about mm.

The cutting blade 17A has a cutting blade portion 17 protruding outward from the outer peripheral surface 170 of the flat roll 17 near the center.
1, and a pair of bending recesses 173a and 173b are provided on both sides of the cutting blade 171. These bending concave portions 173a and 173b have the same depth from the roll center. And, these bending recesses 173a, 1
The outer peripheral surface 17 of the flat roll 17 is
Protrusions 172a, 172b projecting more radially than zero
Is provided. The protruding portions 172a and 172b have a lower protruding height than the cutting blade portion 171, and the cutting blade portion 171 and each of the protruding portions 172a and 172b have a holding position at a position corresponding to the holding groove 195. Grooves 175 and 175 are provided. The width of the holding grooves 175 and 175 matches the width of the holding groove 195, and the depth of the holding grooves 175 and 175 is a molding cut piece 19A described later.
Is smaller than the depth of the groove 195 'of the
A flat steel wire 1b in total with the depth of the groove 195 'of 9A
Has the same size as the width W.

Next, the cutting blade 19A, which is paired with the cutting blade 171 of the forming blade 17A, is provided in the vicinity of the center of the cutting blade 19A.
Two sets of bending projections 193a and 193b corresponding to the bending depressions 173a and 173b are provided on both sides of the projection 91. A concave step 196 into which the cutting blade 171 can enter is formed between the bending protrusion 193 b and the cutting blade 191 in the rotation direction. The two sets of bending projections 193
a, 193b are made equal in height from the center of the roll, and receiving recesses 192a, 1 corresponding to the projections 172a, 172b are provided on both sides of the bending projections 193a, 193b.
92b is formed lower than the outer peripheral surface 190. The height of the bending projections 193a and 193b is, for example, 2.0 to 3.0.
0 mm. The cutting blade portion 191, the bending convex portions 193 a and 193 b, and the receiving concave portions 192 a and 192 are provided.
b has a groove 195 'having a cross-sectional shape similar to the outer surface thereof.
The groove 195 ′ is set to be equal to or slightly shallower than the holding groove 195. Convex part for bending 1
Inverted U-shaped convex portion 193 constituting the groove bottom of 93a, 193b
The a ′ and 193b ′ function as mold portions for the concave portions 50 and 50 of the steel fiber 5, and form the bent portions 5a and 5a with the bending concave portions 173a and 173b. The entirety of the forming and cutting piece 17A and the forming and cutting piece 19A may be formed as one block, or the cutting blade 1
It may be composed of two parts divided at 71 and 191 parts.

Next, a process for producing a steel fiber for reinforcing concrete in the first embodiment will be described. First, each Swift 1
Steel wires 1a, 1a, 1a are drawn from 0, 10, 10 respectively, and the respective steel wires 1a, 1a, 1a are subjected to back tension by the tension adjusting devices 11 described above and are rolled while the length is controlled to be constant. Rolling by passing through the mill 12, and a plurality of flat steel wires 1b, 1b,
1b. In this rolling step, the steel wire is reduced so as to have a width w / thickness t of 2 or more as shown in FIG. This is not possible if w / t is less than 2, since fiber balls are likely to be generated during kneading with concrete. However, if w / t is too large, deformation such as bending occurs during kneading with concrete. Therefore, the upper limit of w / t is generally about 8, and most preferably 2.5 to 5. The cross-sectional shape of the flat steel wire 1b has a vertically long flat shape as shown in FIGS. 8A and 8B. However, as shown in FIG. End faces 101, 1
01 may be a curvature surface, or the thickness direction end surfaces 100 and 100 may be a gentle curvature surface and a width direction end surface 10 as shown in FIG.
1, 101 may be a sharp curvature surface.

The flat steel wires 1b, 1b, 1b subsequently pass through straightening rolls 13, respectively, during which the warps and bends are forcibly applied by the rolls 13a, 13b arranged in a staggered manner, so that the straight flat steel wires 1b, 1b, 1b are moved. 1b and 1b. The flat steel wires 1b, 1b, 1b are guided to the voice 14 so as to be aligned in the width direction, and are transferred to the laminating roll 15 in this state, where the pressing roll 15b and the large-diameter roll 1
5a, a plurality of flat steel wires 1b,
1b, 1b, the end faces 100, 100 in the thickness direction are overlapped with each other to form a stacked bundle. The flat steel wires 1b, 1b, 1b in such a stacked state are sent to the forming and cutting roll 16 via the large-diameter roll 15a. The flat roll 17 and the grooved roll 19 provided on the front end face of the gantry are driven and rotated by a driving mechanism 20. As a result, as shown in FIGS. 5 and 7,
The bending recesses 173a and 173b of the forming and cutting piece 17A and the forming and cutting piece 19A mesh with the bending protrusions 193a and 193b, and the protrusions 172a and 172b mesh with the receiving recesses 192a and 192b. In addition, the cutting blade 17
1 enters the concave step portion 196 while almost in sliding contact with the cutting blade portion 191. The flat steel wires 1b, 1b, 1b in the laminated state are drawn in by the meshing rotation of the forming and cutting piece 17A and the forming and cutting piece 19A, and are formed and cut. Therefore, when starting the work, the flat steel wires 1b, 1b, 1b are preliminarily required to have a flat roll 17 and a grooved roll 19 from the tip.
To be bitten. Thereafter, the molding and cutting speed is arbitrarily set by the rotation speed of the drive mechanism 20.

The molding and cutting process will be described in detail.
Forming cut piece 17 of flat roll 17 and grooved roll 19
In the curved surface portion without A and 19A, the laminated flat steel wire 1b passes through the holding groove 195 at the position where the flat roll 17 and the grooved roll 19 are in contact with or closest to each other. , 100 are sandwiched in an overlapped state, so that they are not subjected to any deformation, and are conveyed downward while being reliably prevented from falling down. Then, at the contact surface or the closest position of the flat roll 17 and the grooved roll 19, the laminated flat steel wires 1b, 1b,
1b is formed by meshing between the forming and cutting pieces 17A and 19A, and is cut (sheared) by the intersection of the cutting blades 171 and 191.

That is, as shown in an enlarged view in FIG. 7, the flat steel wire portion on the downstream side of the cutting blade portions 171 and 191 is engaged with the bending concave portion 173a and the bending convex portion 193a to form the bending concave portion. 173a and inverted U-shaped convex portion 193
a ′, and the flat steel wire portion on the upstream side is bent by the engagement of the bending concave portion 173b and the bending convex portion 193b, and the bent concave portion 173b and the inverted U-shaped convex portion 193 are formed.
b ′ and formed in the vertical direction. In the middle of this bending area, the cutting blade portion 171 of the forming and cutting piece 17A is moved through the concave step portion 196 of the forming and cutting piece 19A.
1, the length direction of the plurality of flat steel wires 1 b is each divided by two in the middle of the bent portion.
The flat roll 17 and the grooved roll 1
9 is rotating, the laminated flat steel wires 1b, 1
b, 1b are conveyed downward, whereby each flat steel wire 1
A plurality of reinforcing steel fibers 5 having bent portions 5a, 5a in the same direction in the same plane as the uneven planes 100, 100 are formed on the front end portion and the rear end portion of b.

The bending recess 173a,
At the time of bending by the 173b and the bending protrusions 193a and 193b, and at the time of shearing by the cutting blades 171 and 191,
The widthwise end faces 101 of the flat steel wires 1b, 1b, 1b, which are stacked in plural, are formed on the protruding portion 1 of the molded cutting piece 17A.
72a, 172b and the bottom of the holding groove 175 provided in the cutting blade part 171 respectively. For this reason, falling can be prevented, and movement is momentarily restrained by friction, so that bending, cutting, and feeding can be reliably performed. The height h of the bent portions 5a, 5a is equal to that of the flat steel wire 1.
It is preferable that the width be equal to or more than の of the width w of b, and the dimensions of the bending concave portions 173a and 173b and the bending portion convex portions 193a and 193b should be set in accordance with this.

As described above, the reinforcing steel fibers 5 in a laminated state as shown in FIG. 8 (c) are manufactured, they are freely dropped from the forming and cutting roll 16, and are stored in the storage container 21c. At the time of this drop, the laminated concrete reinforcing steel fibers 5 are individually separated. Further, since a predetermined vibration is applied to the storage container 21c by a vibration mechanism (not shown) and a magnetic force is applied by the pair of magnets 21a and 21b, the steel fibers are surely separated and the storage direction is set to one. Aligned to the direction. Then, the container 21c may be packed. By storing the steel fibers for concrete reinforcement in the same fiber direction as described above, it is possible to always store a predetermined amount of the steel fibers for concrete reinforcement in the storage container 21c, and to put the steel fibers for concrete reinforcement into the concrete. It is possible to improve the workability at the time of performing and to prevent the fiber ball of the concrete reinforcing steel fiber from being formed.

According to the present invention, the holding groove 1 of the molded cutting piece 19A is provided.
95, 195 'and a groove 175 for holding the molded cutting piece 17A.
, A plurality of flat steel wires 1b, 1b, 1b are introduced to form and cut simultaneously. This is advantageous in increasing the productivity, and the self-sustainability is increased by laminating a plurality of flat steel wires 1b, which are poor in self-sustainability and easily fall, and a state close to the case where the bent portion is formed perpendicular to the uneven plane. This has the advantage that bending can be performed easily. However, when the width / thickness is relatively large, such as about 2,
Although the productivity is reduced, the holding groove 1 of the molded cutting piece 19A is
95, 195 'and a groove 175 for holding the molded cutting piece 17A.
One flat steel wire 1b may be guided to the second wire.

FIGS. 9 and 10 show a second embodiment of the present invention. That is, in the first embodiment, the grooved roll 1 is used.
9 and a single holding groove 195, 195 ′ for the molded cutting piece 19A, but in this embodiment, FIG.
(A) As shown in FIG.
195 'is a plurality of rows. In this case, FIG.
As described above, the holding grooves 175 of the forming and cutting pieces 17A of the flat roll 17 are also provided in a plurality of corresponding rows. The above-mentioned plural rows may be obtained by a laminated structure in which a plurality of flat rolls 17 and grooved rolls 19 shown in FIG. This has the advantage that the number of grooves can be set freely.

In the case where the holding grooves are formed in multiple rows as described above and a plurality of sets of laminated flat steel wires are simultaneously formed and cut to obtain molten steel fibers, the swift 10, the rolling mill 12, and the straightening rolls 13 are used. And a plurality of sets of laminating rolls 15 are used. For example, in the case of two lines, the swift 10, the rolling mill 12, the straightening roll 13, and the laminating roll 15 are arranged facing each other as shown in FIG.
12, a plurality of steel wires 1a are simultaneously supplied and rolled, and the flat steel wires 1b, 1b are straightened by a plurality of straightening rolls 13, 13, respectively. Two sets of flat steel wires 1 each laminated
b and 1b are supplied to the common forming and cutting roll 16,
What is necessary is just to make it convey along the said several holding groove 195,195 '. For more than 3 lines,
The swift 10, the rolling mill 12, the straightening roll 13, and the laminating roll 15 are provided in multiple stages in the height direction, and each laminating roll 1
5 may be arranged out of phase so as to correspond to the holding grooves 195, 195 ', 175.

In the present invention, a step of winding the flat steel wires 1b, 1b, 1b may be interposed between the rolling and the forming and cutting, but preferably the rolling and forming and cutting are performed continuously and continuously. This is because rolling and forming and cutting are independent processes, and once winding onto a bobbin after rolling, it takes time and effort to change over, reducing workability, and furthermore, forming and cutting from the relationship of pulling out from the winding bobbin. If the speed is increased, poor drawing of the flat steel wire from the bobbin frequently occurs, and disconnection or the like occurs. In this method, the cutting limit is 30 m / min. On the other hand, if the rolling and the forming and cutting are continued, the above-mentioned restriction is eliminated.
min forming and cutting can be performed. In each of the above embodiments, the bent portions 5a, 5a are formed only at both longitudinal ends of the steel fiber 5 for concrete reinforcement.
When the bent portions are formed at intervals over the entire length, a grooved bending concave portion and a grooved bending convex portion which can be engaged with each other are formed on the entire circumference of the flat roll 17 and the grooved roll 19, respectively. What is necessary is just to mount the molding top which has. In this case, the cutting section 17A and the forming and cutting section 19A of the above-described embodiment may be used for the cutting location.

[0023]

According to the first and sixth aspects of the present invention, a combination of a flat roll and a grooved roll provided with a special forming and cutting piece by rolling a steel wire and flattening the flat steel wire having a poor autonomy. By forming and cutting the bent portion while preventing falling, the excellent effect of easily and industrially stably producing concrete reinforcing steel fiber with good dispersibility and good reinforcing properties is obtained. can get. According to the second to fourth aspects, since a plurality of flat steel wires are simultaneously formed and cut, an excellent effect that productivity can be improved can be obtained. According to the fifth aspect, since the rolling step and the forming / cutting step are continuous, workability can be improved, and productivity can be improved by increasing the forming / cutting speed. The effect is obtained. According to the sixth aspect, since the abrasion resistance is high, it is possible to realize a long service life that can withstand high-speed molding cutting, and to obtain an excellent effect that it is possible to shorten the production stop time due to the exchange of pieces.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing steps of a method for producing a concrete reinforcing steel fiber according to the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is a perspective view schematically showing a steel fiber manufacturing process according to the present invention.

FIG. 4 is an explanatory view schematically showing an adjustment state before and after rolling in the present invention.

FIG. 5 is a side view showing an example of a forming and cutting step and a flat roll and a grooved roll used for the cutting step.

FIG. 6 is an enlarged perspective view showing a main part of the roll shown in FIG. 5;

FIG. 7 is an enlarged cross-sectional view of a forming and cutting state by the roll of FIG. 5;

8 (a) and 8 (b) are cross-sectional views of a flat steel wire after a rolling step, and FIG. 8 (c) is a perspective view of a formed and cut reinforcing steel fiber.

9A is a partial front view showing another example of the grooved roll used in the embodiment of the present invention, and FIG. 9B is a partial front view showing another example of the flat roll.

FIG. 10 is an explanatory view schematically showing steps of a manufacturing method when the flat roll and the grooved roll of FIG. 9 are used.

DESCRIPTION OF SYMBOLS 1a Steel wire 1b Flat steel wire 5 Reinforcing steel fiber 12 Rolling machine 13 Straightening roll 15 Laminating roll 16 Forming cut roll 17 Flat roll 17A Forming cut piece 19A Grooved roll 19A Forming cut piece 171 Cutting blade portion 172a, 172b Projection portion 173a, 173b Bending concave portion 175 Holding groove 191 Cutting blade portion 193a, 193b Bending convex portion 195, 195 'Holding groove

Claims (7)

(57) [Claims] 1. A cross section having a vertically elongated flat shape and a flat surface 100
In producing the concrete reinforcing steel fiber 5 having the bent portions 5a, 5a at least at both ends in the same plane as above, the steel wire 1a is flattened by rolling means, and then the flat steel wire 1b is formed into a plurality of flat steel wires 1b. Convex portions 193a, 193b for bending
A plurality of formed cutting pieces 19A having a cutting blade portion 191 between them and a bending convex portion and having a flat steel wire holding groove 195 'formed in the circumference thereof are provided on the circumference.
The grooved roll 19 having the flat steel wire holding groove 195 formed on the circumference other than the above, the plurality of bending concave portions 172a, 172b corresponding to the bending convex portions 193a, 193b, and the cutting blade portion 191. It has a cutting blade part 171 and a protruding base part 175 before and after the bending concave parts 172a and 172b.
175, and a flat cutting roll 17 comprising a plurality of forming cut pieces 17A provided on the circumference thereof with grooves 175 for holding a flat steel wire in the cutting blade portion 171 respectively.
6, the flat steel wire 1b is supplied to the flat steel wire rod holding groove 1
95, 175 ', 195' and 175, and the bending convex portions 193a and 193b and the bending concave portions 172a and 173.
A method for producing a steel fiber for concrete reinforcement, characterized in that bent portions 5a, 5a are formed in the same plane as a deviated plane by 2b and cut by cutting blade portions 191, 171. 2. The method for producing a steel fiber for concrete reinforcement according to claim 1, wherein a plurality of said flat steel wires are simultaneously supplied to a forming and cutting roll to be formed and cut. 3. The concrete reinforcement according to claim 2, wherein the flat steel wire is supplied to a flat steel wire holding groove of a forming and cutting roll in a state where a plurality of flat steel wires are stacked so that the flat surfaces are in contact with each other. For producing steel fibers for automobiles. 4. The method according to claim 1, wherein a plurality of steel wires are simultaneously rolled, and the simultaneously rolled flat steel wires are supplied to a forming and cutting roll without being wound on a bobbin, and are formed and cut. Item 4. The method for producing a steel fiber for concrete reinforcement according to any one of Items 3. 5. The production of a steel fiber for reinforcing concrete according to claim 1, which comprises using a flat roll provided with a plurality of flat steel wire holding grooves and a grooved roll. Method. 6. The method for producing a steel fiber for reinforcing concrete according to claim 1, wherein the molding cut piece is made of a cemented carbide piece. 7. The steel fiber for concrete reinforcement has a width / thickness of 2
The method for producing a concrete reinforcing steel fiber according to any one of claims 1 to 6, wherein the length / width is 20 to 45.